{"id":28177,"date":"2026-06-17T10:01:03","date_gmt":"2026-06-17T02:01:03","guid":{"rendered":"https:\/\/www.bestpcbs.com\/blog\/?p=28177"},"modified":"2026-06-17T10:17:38","modified_gmt":"2026-06-17T02:17:38","slug":"120-ohm-resistor","status":"publish","type":"post","link":"https:\/\/www.bestpcbs.com\/blog\/2026\/06\/120-ohm-resistor\/","title":{"rendered":"120 Ohm Resistor: Color Code and CAN Bus Use"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_84 ez-toc-wrap-left counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/06\/120-ohm-resistor\/#What_Is_a_120_Ohm_Resistor\" >What Is a 120 Ohm Resistor?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/06\/120-ohm-resistor\/#120_Ohm_Resistor_Specifications\" >120 Ohm Resistor Specifications<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/06\/120-ohm-resistor\/#What_Is_the_Color_Code_for_a_120_Ohm_Resistor\" >What Is the Color Code for a 120 Ohm Resistor?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/06\/120-ohm-resistor\/#How_to_Read_a_120_Ohm_Resistor_Color_Code\" >How to Read a 120 Ohm Resistor Color Code?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/06\/120-ohm-resistor\/#What_Is_the_SMD_Code_for_a_120_Ohm_Resistor\" >What Is the SMD Code for a 120 Ohm Resistor?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/06\/120-ohm-resistor\/#What_Is_a_120_Ohm_Resistor_Used_For\" >What Is a 120 Ohm Resistor Used For?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/06\/120-ohm-resistor\/#Why_Is_a_120_Ohm_Resistor_Used_in_CAN_Bus\" >Why Is a 120 Ohm Resistor Used in CAN Bus?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/06\/120-ohm-resistor\/#What_Is_a_120_Ohm_Termination_Resistor\" >What Is a 120 Ohm Termination Resistor?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/06\/120-ohm-resistor\/#What_Happens_When_Two_120_Ohm_Resistors_Are_in_Parallel\" >What Happens When Two 120 Ohm Resistors Are in Parallel?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/06\/120-ohm-resistor\/#120_Ohm_Resistor_for_CAN_Bus_RS-485_and_DMX\" >120 Ohm Resistor for CAN Bus, RS-485 and DMX<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/06\/120-ohm-resistor\/#How_to_Choose_a_120_Ohm_Resistor_Wattage_Tolerance_and_Package\" >How to Choose a 120 Ohm Resistor: Wattage, Tolerance and Package<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/06\/120-ohm-resistor\/#Common_Mistakes_When_Selecting_a_120_Ohm_Resistor\" >Common Mistakes When Selecting a 120 Ohm Resistor<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/06\/120-ohm-resistor\/#FAQs_About_120_Ohm_Resistor\" >FAQs About 120 Ohm Resistor<\/a><\/li><\/ul><\/nav><\/div>\n<div class=\"yzp-no-index\"><\/div>\n<p>A 120 ohm resistor is a fixed resistor with a resistance value of 120\u03a9. It is widely used in electronic circuits for current limiting, signal control, voltage division, impedance matching, and communication bus termination.<\/p>\n\n\n\n<p>For many users, the main question is not only \u201cWhat is a 120 ohm resistor?\u201d They also want to know the 120 ohm resistor color code, the<a href=\"https:\/\/www.bestpcbs.com\/blog\/2025\/04\/smd-resistor-sizes-smd-resistor-package-sizes-chart\/\" title=\"\"> SMD resistor<\/a> code, the correct wattage, the suitable package size, and why a 120 ohm resistor is used in CAN bus, RS-485, and DMX termination.<\/p>\n\n\n\n<p>In PCB and PCBA design, a 120\u03a9 resistor may look like a simple component. But if the wrong value, package, power rating, tolerance, or placement is used, the circuit may suffer from communication errors, signal reflection, overheating, or assembly problems.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-4.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"800\" height=\"450\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-4.jpg\" alt=\"120 Ohm Resistor\" class=\"wp-image-28191\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-4.jpg 800w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-4-300x169.jpg 300w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-4-768x432.jpg 768w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><\/a><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"What_Is_a_120_Ohm_Resistor\"><\/span>What Is a 120 Ohm Resistor?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>A 120 ohm resistor is a resistor that limits current or controls signal behavior with a resistance value of 120 ohms. The symbol for ohms is \u03a9, so it may be written as:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>120 ohm resistor<\/li>\n\n\n\n<li>120\u03a9 resistor<\/li>\n\n\n\n<li>120R resistor<\/li>\n\n\n\n<li>resistor 120 ohm<\/li>\n<\/ul>\n\n\n\n<p>The resistor value tells how strongly the component resists current flow. A 120\u03a9 resistor has more resistance than a 100\u03a9 resistor and less resistance than a 150\u03a9 resistor.<\/p>\n\n\n\n<p>In electronics, 120\u03a9 is a common value. It can be used in simple circuits, LED circuits, signal lines, impedance matching, and communication networks. One of its most important uses is as a <strong>termination resistor<\/strong> in CAN bus, RS-485, and DMX systems.<\/p>\n\n\n\n<p>A 120 ohm resistor can come in different forms, including through-hole resistors, SMD resistors, thick film resistors, thin film resistors, precision resistors, power resistors, and termination resistors.<\/p>\n\n\n\n<p>The same 120\u03a9 value can have different wattage ratings, tolerance levels, package sizes, and temperature ratings. This is why resistor selection should not be based on resistance value alone.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"120_Ohm_Resistor_Specifications\"><\/span>120 Ohm Resistor Specifications<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Before selecting a 120 ohm resistor, it is useful to understand the main specifications. These parameters help determine whether the resistor is suitable for a specific circuit, PCB layout, and assembly process.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Parameter<\/th><th class=\"has-text-align-center\" data-align=\"center\">Common Option<\/th><th class=\"has-text-align-center\" data-align=\"center\">Why It Matters<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\">Resistance Value<\/td><td class=\"has-text-align-center\" data-align=\"center\">120\u03a9<\/td><td class=\"has-text-align-center\" data-align=\"center\">The main electrical value used for current control or termination<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">4-Band Color Code<\/td><td class=\"has-text-align-center\" data-align=\"center\">Brown-Red-Brown-Gold<\/td><td class=\"has-text-align-center\" data-align=\"center\">Helps identify through-hole 120\u03a9 resistors<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">5-Band Color Code<\/td><td class=\"has-text-align-center\" data-align=\"center\">Brown-Red-Black-Black-Brown<\/td><td class=\"has-text-align-center\" data-align=\"center\">Used for higher-precision 120\u03a9 resistors<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">SMD Code<\/td><td class=\"has-text-align-center\" data-align=\"center\">121 \/ 120R<\/td><td class=\"has-text-align-center\" data-align=\"center\">Helps identify 120\u03a9 chip resistors<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">Tolerance<\/td><td class=\"has-text-align-center\" data-align=\"center\">\u00b15%, \u00b11%, \u00b10.5%<\/td><td class=\"has-text-align-center\" data-align=\"center\">Affects accuracy and termination consistency<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">Power Rating<\/td><td class=\"has-text-align-center\" data-align=\"center\">1\/8W, 1\/4W, 1\/2W, 1W or higher<\/td><td class=\"has-text-align-center\" data-align=\"center\">Determines heat handling capability<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">Package<\/td><td class=\"has-text-align-center\" data-align=\"center\">0402, 0603, 0805, 1206, axial<\/td><td class=\"has-text-align-center\" data-align=\"center\">Affects PCB space, assembly, rework, and power dissipation<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">Resistor Type<\/td><td class=\"has-text-align-center\" data-align=\"center\">Thick film, thin film, metal film<\/td><td class=\"has-text-align-center\" data-align=\"center\">Affects cost, noise, stability, and precision<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">Common Applications<\/td><td class=\"has-text-align-center\" data-align=\"center\">CAN, RS-485, DMX, signal lines<\/td><td class=\"has-text-align-center\" data-align=\"center\">Defines how the resistor is used in real circuits<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>These specifications are connected. For example, a 120\u03a9 0402 SMD resistor may save PCB space, but it usually has lower power handling than a larger 0805 or 1206 resistor. A precision thin film resistor may offer better tolerance and temperature stability than a standard thick film resistor, but it may cost more.<\/p>\n\n\n\n<p>For simple circuits, a general-purpose 120\u03a9 resistor may be enough. For communication termination, industrial control, automotive electronics, or compact PCBA projects, package, tolerance, placement, and reliability should be checked more carefully.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"What_Is_the_Color_Code_for_a_120_Ohm_Resistor\"><\/span>What Is the Color Code for a 120 Ohm Resistor?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>The most common 120 ohm resistor color code for a 4-band resistor is:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Band<\/th><th class=\"has-text-align-center\" data-align=\"center\">Color<\/th><th class=\"has-text-align-center\" data-align=\"center\">Meaning<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\">1st Band<\/td><td class=\"has-text-align-center\" data-align=\"center\">Brown<\/td><td class=\"has-text-align-center\" data-align=\"center\">1<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">2nd Band<\/td><td class=\"has-text-align-center\" data-align=\"center\">Red<\/td><td class=\"has-text-align-center\" data-align=\"center\">2<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">3rd Band<\/td><td class=\"has-text-align-center\" data-align=\"center\">Brown<\/td><td class=\"has-text-align-center\" data-align=\"center\">\u00d710<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">4th Band<\/td><td class=\"has-text-align-center\" data-align=\"center\">Gold<\/td><td class=\"has-text-align-center\" data-align=\"center\">\u00b15% tolerance<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>So the 4-band color code is:<\/p>\n\n\n\n<p><strong>Brown \u2013 Red \u2013 Brown \u2013 Gold<\/strong><\/p>\n\n\n\n<p>This means:<\/p>\n\n\n\n<p><strong>12 \u00d7 10 = 120\u03a9<\/strong><\/p>\n\n\n\n<p>The gold band means the tolerance is \u00b15%. This means the actual resistance may be slightly higher or lower than 120\u03a9.<\/p>\n\n\n\n<p>For example, a 120\u03a9 \u00b15% resistor may measure approximately between:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>114\u03a9<\/li>\n\n\n\n<li>126\u03a9<\/li>\n<\/ul>\n\n\n\n<p>Some resistors use a 5-band color code for higher precision. A common 5-band 120 ohm resistor color code may be:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Band<\/th><th class=\"has-text-align-center\" data-align=\"center\">Color<\/th><th class=\"has-text-align-center\" data-align=\"center\">Meaning<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\">1st Band<\/td><td class=\"has-text-align-center\" data-align=\"center\">Brown<\/td><td class=\"has-text-align-center\" data-align=\"center\">1<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">2nd Band<\/td><td class=\"has-text-align-center\" data-align=\"center\">Red<\/td><td class=\"has-text-align-center\" data-align=\"center\">2<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">3rd Band<\/td><td class=\"has-text-align-center\" data-align=\"center\">Black<\/td><td class=\"has-text-align-center\" data-align=\"center\">0<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">4th Band<\/td><td class=\"has-text-align-center\" data-align=\"center\">Black<\/td><td class=\"has-text-align-center\" data-align=\"center\">\u00d71<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">5th Band<\/td><td class=\"has-text-align-center\" data-align=\"center\">Brown<\/td><td class=\"has-text-align-center\" data-align=\"center\">\u00b11% tolerance<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>So the 5-band color code is:<\/p>\n\n\n\n<p><strong>Brown \u2013 Red \u2013 Black \u2013 Black \u2013 Brown<\/strong><\/p>\n\n\n\n<p>This means:<\/p>\n\n\n\n<p><strong>120 \u00d7 1 = 120\u03a9<\/strong><\/p>\n\n\n\n<p>The final brown band means the tolerance is \u00b11%.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"How_to_Read_a_120_Ohm_Resistor_Color_Code\"><\/span>How to Read a 120 Ohm Resistor Color Code?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>To read a 120 ohm resistor color code, start from the correct side of the resistor. The tolerance band is usually separated slightly from the other bands. It is often gold, silver, brown, red, or another tolerance color.<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">For a 4-band resistor:<\/mark><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Read the first band as the first digit.<\/li>\n\n\n\n<li>Read the second band as the second digit.<\/li>\n\n\n\n<li>Read the third band as the multiplier.<\/li>\n\n\n\n<li>Read the fourth band as the tolerance.<\/li>\n<\/ul>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">For a 120\u03a9 4-band resistor:<\/mark><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Brown = 1<\/li>\n\n\n\n<li>Red = 2<\/li>\n\n\n\n<li>Brown = \u00d710<\/li>\n\n\n\n<li>Gold = \u00b15%<\/li>\n<\/ul>\n\n\n\n<p>So the value is:<\/p>\n\n\n\n<p><strong>12 \u00d7 10 = 120\u03a9<\/strong><\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-2-1.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"800\" height=\"466\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-2-1.jpg\" alt=\"120 Ohm Resistor\" class=\"wp-image-28190\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-2-1.jpg 800w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-2-1-300x175.jpg 300w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-2-1-768x447.jpg 768w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><\/a><\/figure>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">For a 5-band resistor:<\/mark><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Read the first three bands as the first three digits.<\/li>\n\n\n\n<li>Read the fourth band as the multiplier.<\/li>\n\n\n\n<li>Read the fifth band as the tolerance.<\/li>\n<\/ul>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">For a 120\u03a9 5-band resistor:<\/mark><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Brown = 1<\/li>\n\n\n\n<li>Red = 2<\/li>\n\n\n\n<li>Black = 0<\/li>\n\n\n\n<li>Black = \u00d71<\/li>\n\n\n\n<li>Brown = \u00b11%<\/li>\n<\/ul>\n\n\n\n<p>So the value is:<\/p>\n\n\n\n<p><strong>120 \u00d7 1 = 120\u03a9<\/strong><\/p>\n\n\n\n<p>A common mistake is reading the bands from the wrong direction. If the result looks unusual, check the tolerance band position and confirm the value with a multimeter.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-3-1.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"800\" height=\"462\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-3-1.jpg\" alt=\"120 Ohm Resistor\" class=\"wp-image-28189\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-3-1.jpg 800w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-3-1-300x173.jpg 300w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-3-1-768x444.jpg 768w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><\/a><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"What_Is_the_SMD_Code_for_a_120_Ohm_Resistor\"><\/span>What Is the SMD Code for a 120 Ohm Resistor?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>For SMD resistors, the value is often printed as a number or letter code on the component body. The most common SMD code for a 120 ohm resistor is:<\/p>\n\n\n\n<p><strong>121<\/strong><\/p>\n\n\n\n<p>This means:<\/p>\n\n\n\n<p><strong>12 + 1 zero = 120\u03a9<\/strong><\/p>\n\n\n\n<p>Some SMD resistors may use different markings depending on size, tolerance, and manufacturer.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">SMD Marking<\/th><th class=\"has-text-align-center\" data-align=\"center\">How to Read<\/th><th class=\"has-text-align-center\" data-align=\"center\">Meaning<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\">121<\/td><td class=\"has-text-align-center\" data-align=\"center\">12 + 1 zero<\/td><td class=\"has-text-align-center\" data-align=\"center\">120\u03a9<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">1200<\/td><td class=\"has-text-align-center\" data-align=\"center\">120 \u00d7 10\u2070<\/td><td class=\"has-text-align-center\" data-align=\"center\">120\u03a9<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">120R<\/td><td class=\"has-text-align-center\" data-align=\"center\">120 ohms<\/td><td class=\"has-text-align-center\" data-align=\"center\">120\u03a9<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">120\u03a9<\/td><td class=\"has-text-align-center\" data-align=\"center\">Direct marking<\/td><td class=\"has-text-align-center\" data-align=\"center\">120\u03a9<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">R120<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.120 ohms<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.120\u03a9, not 120\u03a9<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>The difference between <strong>120R<\/strong> and <strong>R120<\/strong> is important.<\/p>\n\n\n\n<p>In resistor markings, the letter R is often used to replace the decimal point, especially for low-value resistors. When R appears in the middle or at the beginning of the number, it usually works like a decimal point. When R appears after the number, it usually means ohms.<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">For example:<\/mark><\/strong><\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Marking<\/th><th class=\"has-text-align-center\" data-align=\"center\">How to Read<\/th><th class=\"has-text-align-center\" data-align=\"center\">Resistance<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\">120R<\/td><td class=\"has-text-align-center\" data-align=\"center\">120 ohms<\/td><td class=\"has-text-align-center\" data-align=\"center\">120\u03a9<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">R120<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.120 ohms<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.120\u03a9<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">1R20<\/td><td class=\"has-text-align-center\" data-align=\"center\">1.20 ohms<\/td><td class=\"has-text-align-center\" data-align=\"center\">1.2\u03a9<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">0R12<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.12 ohms<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.12\u03a9<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">4R7<\/td><td class=\"has-text-align-center\" data-align=\"center\">4.7 ohms<\/td><td class=\"has-text-align-center\" data-align=\"center\">4.7\u03a9<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>So:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>120R<\/strong> usually means 120\u03a9.<\/li>\n\n\n\n<li><strong>R120<\/strong> usually means 0.120\u03a9.<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-1-1.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"768\" height=\"400\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-1-1.jpg\" alt=\"120 Ohm Resistor\" class=\"wp-image-28185\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-1-1.jpg 768w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-1-1-300x156.jpg 300w\" sizes=\"auto, (max-width: 768px) 100vw, 768px\" \/><\/a><\/figure>\n\n\n\n<p>These are completely different resistance values. A 120\u03a9 resistor is commonly used for signal control or termination. A 0.120\u03a9 resistor is a very low-value resistor and may be used for current sensing or power circuits. Using the wrong marking can cause circuit failure.<\/p>\n\n\n\n<p>Small SMD resistors, such as 0402 or 0201 packages, may not have visible markings. In that case, the value should be confirmed from the BOM, schematic, placement file, reel label, or measurement.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"What_Is_a_120_Ohm_Resistor_Used_For\"><\/span>What Is a 120 Ohm Resistor Used For?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>A 120 ohm resistor can be used in many electronic circuits. The exact function depends on where it is placed in the circuit.<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">Common uses include:<\/mark><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Current limiting<\/li>\n\n\n\n<li>Signal conditioning<\/li>\n\n\n\n<li>Voltage division<\/li>\n\n\n\n<li>Pull-up or pull-down circuits<\/li>\n\n\n\n<li>LED current control<\/li>\n\n\n\n<li>Impedance matching<\/li>\n\n\n\n<li>Communication bus termination<\/li>\n\n\n\n<li>CAN bus termination<\/li>\n\n\n\n<li>RS-485 termination<\/li>\n\n\n\n<li>DMX termination<\/li>\n\n\n\n<li>Industrial control circuits<\/li>\n\n\n\n<li>Automotive electronics<\/li>\n\n\n\n<li>Embedded systems<\/li>\n\n\n\n<li>PCB signal lines<\/li>\n<\/ul>\n\n\n\n<p>Among these applications, one of the most important uses is termination. In high-speed or long-distance communication lines, a termination resistor helps reduce signal reflection and improve signal integrity.<\/p>\n\n\n\n<p>For example, CAN bus networks often use 120\u03a9 termination resistors at both ends of the bus. RS-485 and DMX systems may also use 120\u03a9 termination depending on cable impedance, network length, and data rate.<\/p>\n\n\n\n<p>In PCB assembly, 120\u03a9 resistors may be placed near connectors, transceivers, communication interfaces, or differential signal lines. Placement matters because a termination resistor should normally be located near the end of the transmission line, not randomly placed in the circuit.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Why_Is_a_120_Ohm_Resistor_Used_in_CAN_Bus\"><\/span>Why Is a 120 Ohm Resistor Used in CAN Bus?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>A 120 ohm resistor is used in CAN bus as a termination resistor. Its purpose is to match the characteristic impedance of the CAN bus cable or transmission line and reduce signal reflections.<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">CAN bus is a differential communication system. It uses two signal lines:<\/mark><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>CAN_H<\/li>\n\n\n\n<li>CAN_L<\/li>\n<\/ul>\n\n\n\n<p>When signals travel along a cable or PCB trace, they can reflect back if the line is not properly terminated. These reflections may distort the signal and cause communication errors.<\/p>\n\n\n\n<p>A 120\u03a9 termination resistor is commonly placed across CAN_H and CAN_L at each end of the CAN bus. This helps absorb signal energy and reduce reflection.<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">A typical CAN bus uses:<\/mark><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>One 120\u03a9 resistor at one end of the bus<\/li>\n\n\n\n<li>One 120\u03a9 resistor at the other end of the bus<\/li>\n<\/ul>\n\n\n\n<p>The 120\u03a9 value is used because it is close to the typical characteristic impedance of many CAN bus twisted-pair cables. Correct termination helps the signal remain clean, especially in longer networks or noisy environments.<\/p>\n\n\n\n<p>In automotive electronics, industrial control systems, battery management systems, and embedded devices, correct CAN bus termination is important for reliable communication.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"What_Is_a_120_Ohm_Termination_Resistor\"><\/span>What Is a 120 Ohm Termination Resistor?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>A 120 ohm termination resistor is a resistor placed at the end of a transmission line to reduce signal reflections. It is commonly used in differential communication systems.<\/p>\n\n\n\n<p>A termination resistor is not just a normal resistor placed anywhere. Its position matters.<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">It should usually be placed:<\/mark><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>At the end of the communication bus<\/li>\n\n\n\n<li>Across the differential signal pair<\/li>\n\n\n\n<li>Close to the connector or transceiver endpoint<\/li>\n\n\n\n<li>According to the communication standard and layout requirement<\/li>\n<\/ul>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">Common systems that may use 120\u03a9 termination include:<\/mark><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>CAN bus<\/li>\n\n\n\n<li>RS-485<\/li>\n\n\n\n<li>Modbus over RS-485<\/li>\n\n\n\n<li>DMX512<\/li>\n\n\n\n<li>Industrial communication networks<\/li>\n\n\n\n<li>Automotive communication circuits<\/li>\n<\/ul>\n\n\n\n<p>The goal is to make the transmission line behave more predictably. Without correct termination, the signal may reflect, ring, overshoot, undershoot, or become unstable.<\/p>\n\n\n\n<p>A 120 ohm termination resistor is especially important when the cable is long, the signal speed is high, the environment is noisy, the bus has multiple nodes, or communication reliability is critical.<\/p>\n\n\n\n<p>In PCB layout, the termination resistor should be placed carefully. Poor placement can reduce its effectiveness even if the resistor value is correct.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"What_Happens_When_Two_120_Ohm_Resistors_Are_in_Parallel\"><\/span>What Happens When Two 120 Ohm Resistors Are in Parallel?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>When two 120 ohm resistors are connected in parallel, the equivalent resistance is 60 ohms.<\/p>\n\n\n\n<p>This is an important point in CAN bus testing.<\/p>\n\n\n\n<p>A standard CAN bus often has one 120\u03a9 termination resistor at each end of the bus. Because these two resistors are connected across the same CAN_H and CAN_L pair, they appear in parallel when measured from the bus.<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">The equivalent resistance is:<\/mark><\/strong><\/p>\n\n\n\n<p><strong>120\u03a9 || 120\u03a9 = 60\u03a9<\/strong><\/p>\n\n\n\n<p>That is why technicians often measure about <strong>60\u03a9<\/strong> between CAN_H and CAN_L when the system is powered off and both termination resistors are installed.<\/p>\n\n\n\n<p>This does not mean each resistor is 60\u03a9. It means the two 120\u03a9 resistors together create a 60\u03a9 equivalent resistance.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Network Condition<\/th><th class=\"has-text-align-center\" data-align=\"center\">Measured Resistance Between CAN_H and CAN_L<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\">One 120\u03a9 termination resistor installed<\/td><td class=\"has-text-align-center\" data-align=\"center\">About 120\u03a9<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">Two 120\u03a9 termination resistors installed<\/td><td class=\"has-text-align-center\" data-align=\"center\">About 60\u03a9<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">No termination resistor installed<\/td><td class=\"has-text-align-center\" data-align=\"center\">Very high or open<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">Too many termination resistors installed<\/td><td class=\"has-text-align-center\" data-align=\"center\">Lower than 60\u03a9<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>If you measure around 60\u03a9 on a CAN bus, it usually means both termination resistors are present. If the reading is around 120\u03a9, one termination resistor may be missing. If the reading is much lower than 60\u03a9, there may be extra termination or another fault.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"120_Ohm_Resistor_for_CAN_Bus_RS-485_and_DMX\"><\/span>120 Ohm Resistor for CAN Bus, RS-485 and DMX<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>A 120 ohm resistor is commonly used in several communication systems because many differential communication cables have characteristic impedance near 120\u03a9.<\/p>\n\n\n\n<p><strong>CAN Bus<\/strong><\/p>\n\n\n\n<p>In CAN bus, a 120\u03a9 resistor is usually placed across CAN_H and CAN_L at each end of the bus. This reduces signal reflection and helps maintain reliable communication.<\/p>\n\n\n\n<p>Typical applications include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Automotive control modules<\/li>\n\n\n\n<li>Battery management systems<\/li>\n\n\n\n<li>Industrial controllers<\/li>\n\n\n\n<li>Robotics<\/li>\n\n\n\n<li>Vehicle diagnostic systems<\/li>\n\n\n\n<li>Embedded communication boards<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-5.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"576\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-5-1024x576.jpg\" alt=\"120 Ohm Resistor\" class=\"wp-image-28192\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-5-1024x576.jpg 1024w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-5-300x169.jpg 300w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-5-768x432.jpg 768w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-5-1536x864.jpg 1536w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-5.jpg 1672w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/a><\/figure>\n\n\n\n<p><strong>RS-485<\/strong><\/p>\n\n\n\n<p>RS-485 is also a differential communication standard. It may use a 120\u03a9 termination resistor across the A and B lines at the end of the bus.<\/p>\n\n\n\n<p>RS-485 is common in:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Industrial automation<\/li>\n\n\n\n<li>Modbus networks<\/li>\n\n\n\n<li>Motor controllers<\/li>\n\n\n\n<li>Sensors<\/li>\n\n\n\n<li>Building control systems<\/li>\n\n\n\n<li>Long-distance serial communication<\/li>\n<\/ul>\n\n\n\n<p>Not every RS-485 network needs termination, especially if the cable is short or the data rate is low. But for longer cables or higher speeds, termination becomes more important.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-7.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"576\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-7-1024x576.jpg\" alt=\"120 Ohm Resistor\" class=\"wp-image-28193\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-7-1024x576.jpg 1024w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-7-300x169.jpg 300w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-7-768x432.jpg 768w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-7-1536x864.jpg 1536w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-7.jpg 1672w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/a><\/figure>\n\n\n\n<p><strong>DMX<\/strong><\/p>\n\n\n\n<p>DMX512 lighting systems often use a 120\u03a9 terminator at the end of the DMX line. This helps reduce signal reflection and improve communication stability.<\/p>\n\n\n\n<p>DMX termination is common in:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Stage lighting<\/li>\n\n\n\n<li>LED controllers<\/li>\n\n\n\n<li>Theater systems<\/li>\n\n\n\n<li>Architectural lighting<\/li>\n\n\n\n<li>Entertainment control systems<\/li>\n<\/ul>\n\n\n\n<p>In all these systems, the resistor value is only one part of the design. Cable impedance, bus length, data rate, connector layout, and PCB routing also affect signal quality.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-6.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"576\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-6-1024x576.jpg\" alt=\"120 Ohm Resistor\" class=\"wp-image-28194\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-6-1024x576.jpg 1024w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-6-300x169.jpg 300w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-6-768x432.jpg 768w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-6-1536x864.jpg 1536w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-6.jpg 1672w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/a><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"How_to_Choose_a_120_Ohm_Resistor_Wattage_Tolerance_and_Package\"><\/span>How to Choose a 120 Ohm Resistor: Wattage, Tolerance and Package<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Choosing a 120 ohm resistor should not be based only on resistance value. You should also check wattage, tolerance, package size, resistor type, temperature rating, and application.<\/p>\n\n\n\n<p><strong>Wattage<\/strong><\/p>\n\n\n\n<p>Wattage tells how much power the resistor can safely dissipate as heat.<\/p>\n\n\n\n<p>Common 120 ohm resistor power ratings include:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Power Rating<\/th><th class=\"has-text-align-center\" data-align=\"center\">Typical Use<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\">1\/8 W<\/td><td class=\"has-text-align-center\" data-align=\"center\">Small signal circuits<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">1\/4 W<\/td><td class=\"has-text-align-center\" data-align=\"center\">General through-hole circuits<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">1\/2 W<\/td><td class=\"has-text-align-center\" data-align=\"center\">Higher power margin<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">1 W<\/td><td class=\"has-text-align-center\" data-align=\"center\">Power or industrial circuits<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">5 W or higher<\/td><td class=\"has-text-align-center\" data-align=\"center\">Special power applications<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>For many signal termination applications, the power is usually low. But the correct rating should still be checked based on voltage, current, duty cycle, thermal environment, and derating requirement.<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">The power can be estimated with:<\/mark><\/strong><\/p>\n\n\n\n<p><strong>P = V\u00b2 \/ R<\/strong><\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">For example, if a 5V signal is continuously applied across a 120\u03a9 resistor:<\/mark><\/strong><\/p>\n\n\n\n<p><strong>P = 5\u00b2 \/ 120 = 25 \/ 120 = 0.208 W<\/strong><\/p>\n\n\n\n<p>In this case, a 1\/4W resistor may be close to the limit, depending on real operating conditions and derating. A higher wattage may be safer.<\/p>\n\n\n\n<p>The calculated power is only a starting point. In real PCB design, resistor temperature also depends on package size, copper area, airflow, nearby heat sources, ambient temperature, and how long the load is applied.<\/p>\n\n\n\n<p><strong>Tolerance<\/strong><\/p>\n\n\n\n<p>Tolerance tells how close the real resistance value is to the marked value.<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">Common tolerances include:<\/mark><\/strong><\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Tolerance<\/th><th class=\"has-text-align-center\" data-align=\"center\">Meaning<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\">\u00b15%<\/td><td class=\"has-text-align-center\" data-align=\"center\">General use<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">\u00b11%<\/td><td class=\"has-text-align-center\" data-align=\"center\">More precise circuits<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">\u00b10.5% or lower<\/td><td class=\"has-text-align-center\" data-align=\"center\">Precision applications<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>For CAN bus, RS-485, DMX, and signal termination, \u00b11% or \u00b15% may be used depending on the design requirement. For precision analog circuits, tighter tolerance may be needed.<\/p>\n\n\n\n<p><strong>Package<\/strong><\/p>\n\n\n\n<p>A 120 ohm resistor can be made as a through-hole resistor or an <a href=\"https:\/\/www.bestpcbs.com\/blog\/2025\/12\/smd-resistor-dimensions\/\" title=\"\">SMD resistor<\/a>. For PCB assembly, the package affects board space, power rating, assembly yield, inspection, and rework.<\/p>\n\n\n\n<p>For SMD resistors, package numbers such as 0201, 0402, 0603, 0805, and 1206 refer to physical size. For example, a 0402 resistor is about 1.0 \u00d7 0.5 mm, while a 0603 resistor is about 1.6 \u00d7 0.8 mm. These numbers describe the resistor package size, not the resistance value. A 120\u03a9 resistor can be supplied in many SMD packages.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">SMD Package<\/th><th class=\"has-text-align-center\" data-align=\"center\">Dimensions (mm)<\/th><th class=\"has-text-align-center\" data-align=\"center\">Dimensions (inch)<\/th><th class=\"has-text-align-center\" data-align=\"center\">Typical Use<\/th><th class=\"has-text-align-center\" data-align=\"center\">Selection Note<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\">0201<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.6 \u00d7 0.3<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.024 \u00d7 0.012<\/td><td class=\"has-text-align-center\" data-align=\"center\">Very compact electronics<\/td><td class=\"has-text-align-center\" data-align=\"center\">Saves space but is difficult to assemble and rework<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">0402<\/td><td class=\"has-text-align-center\" data-align=\"center\">1.0 \u00d7 0.5<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.040 \u00d7 0.020<\/td><td class=\"has-text-align-center\" data-align=\"center\">Compact PCB layouts<\/td><td class=\"has-text-align-center\" data-align=\"center\">Good for high-density boards but needs controlled SMT process<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">0603<\/td><td class=\"has-text-align-center\" data-align=\"center\">1.6 \u00d7 0.8<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.063 \u00d7 0.031<\/td><td class=\"has-text-align-center\" data-align=\"center\">General SMT assembly<\/td><td class=\"has-text-align-center\" data-align=\"center\">Good balance of size, cost, and manufacturability<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">0805<\/td><td class=\"has-text-align-center\" data-align=\"center\">2.0 \u00d7 1.25<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.079 \u00d7 0.049<\/td><td class=\"has-text-align-center\" data-align=\"center\">Easier inspection and rework<\/td><td class=\"has-text-align-center\" data-align=\"center\">Better process margin and higher power options<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">1206<\/td><td class=\"has-text-align-center\" data-align=\"center\">3.2 \u00d7 1.6<\/td><td class=\"has-text-align-center\" data-align=\"center\">0.126 \u00d7 0.063<\/td><td class=\"has-text-align-center\" data-align=\"center\">Higher power margin<\/td><td class=\"has-text-align-center\" data-align=\"center\">Useful when heat, reliability, or manual rework matters<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>A smaller SMD package saves PCB space, but it usually has lower power handling and is harder to inspect or rework. A larger SMD package takes more board space, but it can provide better power margin, stronger solder joints, and easier manual handling.<\/p>\n\n\n\n<p>Through-hole 120 ohm resistors are different. They do not use the same 0201\/0402\/0603 size code system. Their physical size usually depends on power rating, body style, lead spacing, and manufacturer specification. They are easier for manual soldering, prototypes, and repair, but they take more PCB space than SMD resistors.<\/p>\n\n\n\n<p><strong>Resistor Type<\/strong><\/p>\n\n\n\n<p>The resistor type also matters.<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">Common options include:<\/mark><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Thick film resistor<\/li>\n\n\n\n<li>Thin film resistor<\/li>\n\n\n\n<li>Metal film resistor<\/li>\n\n\n\n<li>Current sense resistor<\/li>\n\n\n\n<li>Precision resistor<\/li>\n\n\n\n<li>Power resistor<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-8.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"728\" height=\"478\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-8.jpg\" alt=\"120 ohm resistor\" class=\"wp-image-28196\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-8.jpg 728w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/06\/120-ohm-resistor-8-300x197.jpg 300w\" sizes=\"auto, (max-width: 728px) 100vw, 728px\" \/><\/a><\/figure>\n\n\n\n<p>For most digital circuits and communication termination applications, a standard thick film or thin film resistor may be enough. For precision circuits, low-noise or tighter-tolerance resistors may be required.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Common_Mistakes_When_Selecting_a_120_Ohm_Resistor\"><\/span>Common Mistakes When Selecting a 120 Ohm Resistor<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>A 120\u03a9 resistor is simple, but selection mistakes can still cause circuit problems.<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">Common mistakes include:<\/mark><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Choosing only by resistance value and ignoring wattage<\/li>\n\n\n\n<li>Confusing 120R with R120<\/li>\n\n\n\n<li>Using 120k\u03a9 instead of 120\u03a9<\/li>\n\n\n\n<li>Replacing 120\u03a9 with 100\u03a9 or 150\u03a9 in termination circuits without checking the design<\/li>\n\n\n\n<li>Using too small a package for the required power<\/li>\n\n\n\n<li>Ignoring tolerance in communication or precision circuits<\/li>\n\n\n\n<li>Placing the termination resistor too far from the bus endpoint<\/li>\n\n\n\n<li>Assuming every RS-485 network needs termination without checking cable length and speed<\/li>\n\n\n\n<li>Not checking the BOM, schematic, datasheet, or layout before replacement<\/li>\n<\/ul>\n\n\n\n<p>For simple current-limiting circuits, a nearby resistor value may sometimes work after calculation. For CAN bus, RS-485, DMX, impedance matching, and signal integrity applications, resistor replacement should be checked carefully.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"FAQs_About_120_Ohm_Resistor\"><\/span>FAQs About 120 Ohm Resistor<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p><strong>What Is a 120 Ohm Resistor?<\/strong><\/p>\n\n\n\n<p>A 120 ohm resistor is a resistor with a resistance value of 120\u03a9. It is used to limit current, control signals, divide voltage, and terminate communication lines.<\/p>\n\n\n\n<p><strong>What Is the Color Code for a 120 Ohm Resistor?<\/strong><\/p>\n\n\n\n<p>The common 4-band color code for a 120 ohm resistor is <strong>Brown \u2013 Red \u2013 Brown \u2013 Gold<\/strong>. This represents 12 \u00d7 10 = 120\u03a9 with \u00b15% tolerance.<\/p>\n\n\n\n<p><strong>What Is the 5-Band Color Code for a 120 Ohm Resistor?<\/strong><\/p>\n\n\n\n<p>A common 5-band 120 ohm resistor color code is <strong>Brown \u2013 Red \u2013 Black \u2013 Black \u2013 Brown<\/strong>. This represents 120 \u00d7 1 = 120\u03a9 with \u00b11% tolerance.<\/p>\n\n\n\n<p><strong>What Is the SMD Code for a 120 Ohm Resistor?<\/strong><\/p>\n\n\n\n<p>The most common SMD code for a 120 ohm resistor is <strong>121<\/strong>. This means 12 followed by one zero, or 120\u03a9.<\/p>\n\n\n\n<p><strong>Is 120R the Same as 120 Ohm?<\/strong><\/p>\n\n\n\n<p>Yes. In resistor marking, <strong>120R<\/strong> usually means 120\u03a9. The letter R is used as the ohm marker.<\/p>\n\n\n\n<p><strong>Is R120 the Same as 120 Ohm?<\/strong><\/p>\n\n\n\n<p>No. <strong>R120<\/strong> usually means 0.120\u03a9, not 120\u03a9. In low-value resistor markings, the letter R is often used as a decimal point. That is why R120 is read as 0.120\u03a9.<\/p>\n\n\n\n<p><strong>Why Is a 120 Ohm Resistor Used in CAN Bus?<\/strong><\/p>\n\n\n\n<p>A 120 ohm resistor is used in CAN bus to terminate the differential signal line and reduce signal reflections. It is usually placed across CAN_H and CAN_L at both ends of the bus.<\/p>\n\n\n\n<p><strong>Why Does CAN Bus Measure 60 Ohms?<\/strong><\/p>\n\n\n\n<p>A CAN bus with two 120\u03a9 termination resistors will measure about 60\u03a9 between CAN_H and CAN_L because the two 120\u03a9 resistors are connected in parallel.<\/p>\n\n\n\n<p><strong>Can I Replace a 120 Ohm Resistor with 100 Ohm or 150 Ohm?<\/strong><\/p>\n\n\n\n<p>It depends on the circuit. For simple current limiting, a nearby value may sometimes work after calculation. For CAN bus, RS-485, DMX, and impedance matching, do not replace 120\u03a9 without checking the design requirement.<\/p>\n\n\n\n<p><strong>What Wattage Should a 120 Ohm Resistor Be?<\/strong><\/p>\n\n\n\n<p>The wattage depends on voltage, current, duty cycle, ambient temperature, and heat dissipation. Common choices include 1\/8W, 1\/4W, 1\/2W, and 1W. Always calculate power and apply a safety margin.<\/p>\n\n\n\n<p><strong>Is a 120 Ohm Resistor Polarized?<\/strong><\/p>\n\n\n\n<p>No. A resistor is not polarized. It can be installed in either direction unless the package or circuit has a special mechanical requirement.<\/p>\n\n\n\n<p><strong>Where Is a 120 Ohm Termination Resistor Placed?<\/strong><\/p>\n\n\n\n<p>A 120 ohm termination resistor is usually placed at the end of a communication bus and across the differential signal pair, such as CAN_H and CAN_L or RS-485 A and B lines.<\/p>\n\n\n\n<p>To sum up, a 120 ohm resistor is a common resistor value used in many electronic circuits. Its key points include color-code identification, SMD marking, resistor specifications, package selection, and communication bus termination.<\/p>\n\n\n\n<p>For through-hole resistors, the common 120 ohm resistor color code is <strong>Brown \u2013 Red \u2013 Brown \u2013 Gold<\/strong>. For SMD resistors, the common marking is <strong>121<\/strong>. In CAN bus, RS-485, and DMX systems, a 120\u03a9 termination resistor helps reduce signal reflections and improve communication reliability.<\/p>\n\n\n\n<p>When choosing a 120 ohm resistor, check more than the resistance value. Wattage, tolerance, package, resistor type, PCB placement, and application requirements all matter.<\/p>\n\n\n\n<p>Need support with <a href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/02\/full-turnkey-pcb-assembly\/\" title=\"\">full turnkey PCB assembly<\/a>, BOM review, resistor selection, or DFM checking? Pls feel free to send your Gerber files, BOM, stack-up, and project requirements to EBest Circuit (Best Technology) at <strong>sales@bestpcbs.com<\/strong>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>A 120 ohm resistor is a fixed resistor with a resistance value of 120\u03a9. It is widely used in electronic circuits for current limiting, signal control, voltage division, impedance matching, and communication bus termination. For many users, the main question is not only \u201cWhat is a 120 ohm resistor?\u201d They also want to know the [&hellip;]<\/p>\n","protected":false},"author":33085,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_uf_show_specific_survey":0,"_uf_disable_surveys":false,"footnotes":""},"categories":[175,174,5341],"tags":[6269,6270,6271],"class_list":["post-28177","post","type-post","status-publish","format-standard","hentry","category-best-pcb","category-bestpcb","category-electrical-components","tag-120-ohm-resistor","tag-120-ohm-resistor-color-code","tag-120-ohm-resistor-for-can-bus"],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/posts\/28177","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/users\/33085"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/comments?post=28177"}],"version-history":[{"count":6,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/posts\/28177\/revisions"}],"predecessor-version":[{"id":28204,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/posts\/28177\/revisions\/28204"}],"wp:attachment":[{"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/media?parent=28177"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/categories?post=28177"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/tags?post=28177"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}