{"id":67381,"date":"2026-10-21T10:09:08","date_gmt":"2026-10-21T07:09:08","guid":{"rendered":"https:\/\/wpcalc.com\/en\/?p=67381"},"modified":"2026-10-21T10:09:08","modified_gmt":"2026-10-21T07:09:08","slug":"voltage-divider-calculator","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/engineering\/voltage-divider-calculator\/","title":{"rendered":"Voltage Divider Calculator"},"content":{"rendered":"<section class=\"not-prose calculator-box\" aria-labelledby=\"calculator-title\"><div class=\"flex items-baseline sm:items-center justify-between gap-2 sm:gap-3\"><div class=\"flex flex-col sm:flex-row sm:items-center gap-2\"><span class=\"icon icon-calculator text-primary-700! text-base! dark:text-primary-300!\" aria-hidden=\"true\"><\/span><h2 id=\"calculator-title\" class=\"text-lg font-display font-bold\">Solve Your Resistive Voltage Divider<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"67381\" data-favorite-title=\"Voltage Divider\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/engineering\/voltage-divider-calculator\/\" data-favorite-excerpt=\"Calculate the output voltage of a resistive voltage divider, or solve for Vin, R1 or R2. Enter your values, add an optional load resistance, or find the closest standard E-series resistor pair for a target ratio.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-electrical\">\n    <span class=\"icon icon-shape-star-empty\" aria-hidden=\"true\"><\/span>\n  <\/button>\n  <div class=\"calcdash-favorite__tip\" aria-hidden=\"true\">\n   <span class=\"favorite-tooltip\" id=\"favorite-tooltip\"><\/span>\n  <\/div>\n  <span class=\"sr-only\" role=\"status\" id=\"favorite-status\"><\/span>\n<\/div><\/div><form action=\"https:\/\/wpcalc.com\/en\/engineering\/voltage-divider-calculator\/\" method=\"POST\" class=\"calculator\" id=\"calculator-67381\" data-post=\"67381\"><fieldset class=\"fieldset-input is-2\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field\" id=\"input-1\"><label for=\"field-1\">Solve for<\/label><div class=\"grid grid-cols-1\"><select id=\"field-1\" name=\"solve_for\"><option value=\"vout\" selected>Vout from Vin, R1, R2<\/option><option value=\"vin\">Vin from Vout, R1, R2<\/option><option value=\"r1\">R1 from Vin, Vout, R2<\/option><option value=\"r2\">R2 from Vin, Vout, R1<\/option><option value=\"std\">Standard resistor pair (E-series)<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><div class=\"field has-term\" id=\"input-2\"><label for=\"field-2\">Input voltage (Vin)<\/label><div class=\"term\">Vin<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><div class=\"field-group\"><input type=\"text\" name=\"input_voltage_vin\" id=\"field-2\" aria-describedby=\"calc-info-2\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 12\" min=\"0\" value=\"12\"\/><div class=\"grid grid-cols-1\"><select id=\"field-3\" name=\"voltage_unit\" aria-label=\"Voltage unit\"><option value=\"v\" selected>V<\/option><option value=\"mv\">mV<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><small id=\"calc-info-2\">Supply voltage applied across the whole divider<\/small><\/div><div class=\"field has-term\" id=\"input-3\" hidden><label for=\"field-4\">Output voltage (Vout)<\/label><div class=\"term\">Vout<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><div class=\"field-group\"><input type=\"text\" name=\"output_voltage_vout\" id=\"field-4\" aria-describedby=\"calc-info-4\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 5\" min=\"0\" value=\"5\"\/><div class=\"grid grid-cols-1\"><select id=\"field-5\" name=\"voltage_unit\" aria-label=\"Voltage unit\"><option value=\"v\" selected>V<\/option><option value=\"mv\">mV<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><small id=\"calc-info-4\">Voltage you want at the tap<\/small><\/div><div class=\"field has-term\" id=\"input-4\"><label for=\"field-6\">Resistor R1 (top)<\/label><div class=\"term\">R1<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><div class=\"field-group\"><input type=\"text\" name=\"resistor_r1_top\" id=\"field-6\" aria-describedby=\"calc-info-6\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 10\" min=\"0\" value=\"10000\"\/><div class=\"grid grid-cols-1\"><select id=\"field-7\" name=\"r1_unit\" aria-label=\"R1 unit\"><option value=\"ohm\">\u03a9<\/option><option value=\"k\" selected>k\u03a9<\/option><option value=\"m\">M\u03a9<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><small id=\"calc-info-6\">Resistor between Vin and the tap<\/small><\/div><div class=\"field has-term\" id=\"input-5\"><label for=\"field-8\">Resistor R2 (bottom)<\/label><div class=\"term\">R2<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><div class=\"field-group\"><input type=\"text\" name=\"resistor_r2_bottom\" id=\"field-8\" aria-describedby=\"calc-info-8\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 8.2\" min=\"0\" value=\"8200\"\/><div class=\"grid grid-cols-1\"><select id=\"field-9\" name=\"r2_unit\" aria-label=\"R2 unit\"><option value=\"ohm\">\u03a9<\/option><option value=\"k\" selected>k\u03a9<\/option><option value=\"m\">M\u03a9<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><small id=\"calc-info-8\">Resistor between the tap and ground<\/small><\/div><div class=\"field has-term\" id=\"input-6\"><label for=\"field-10\">Load resistance (RL)<\/label><div class=\"term\">RL<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><div class=\"field-group\"><input type=\"text\" name=\"load_resistance_rl\" id=\"field-10\" aria-describedby=\"calc-info-10\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 100\" min=\"0\" value=\"0\"\/><div class=\"grid grid-cols-1\"><select id=\"field-11\" name=\"rl_unit\" aria-label=\"RL unit\"><option value=\"ohm\">\u03a9<\/option><option value=\"k\" selected>k\u03a9<\/option><option value=\"m\">M\u03a9<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><small id=\"calc-info-10\">Load wired in parallel with R2 \u2014 enter 0 or leave empty for no load<\/small><\/div><div class=\"field is-single has-term\" id=\"input-7\" hidden><label for=\"field-12\">Target ratio (Vout\/Vin)<\/label><div class=\"term\">Vout\/Vin<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"target_ratio_voutvin\" id=\"field-12\" aria-describedby=\"calc-info-12\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 0.45\" min=\"0\" max=\"1\" value=\"0.45\"\/><small id=\"calc-info-12\">Desired fraction of Vin at the tap, e.g. 0.5 for half the supply<\/small><\/div><div class=\"field is-single\" id=\"input-8\" hidden><label for=\"field-13\">Resistor series<\/label><div class=\"grid grid-cols-1\"><select id=\"field-13\" name=\"resistor_series\"><option value=\"e12\">E12 (\u00b110%)<\/option><option value=\"e24\" selected>E24 (\u00b15%)<\/option><option value=\"e96\">E96 (\u00b11%)<\/option><\/select><svg class=\"pointer-events-none col-start-1 row-start-1 mr-2 size-5 self-center justify-self-end text-gray-500 sm:size-4\" viewBox=\"0 0 16 16\" fill=\"currentColor\" aria-hidden=\"true\" data-slot=\"icon\">\n              <path fill-rule=\"evenodd\" d=\"M4.22 6.22a.75.75 0 0 1 1.06 0L8 8.94l2.72-2.72a.75.75 0 1 1 1.06 1.06l-3.25 3.25a.75.75 0 0 1-1.06 0L4.22 7.28a.75.75 0 0 1 0-1.06Z\" clip-rule=\"evenodd\" \/>\n            <\/svg><\/div><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"67381\">Calculate<\/button><button type=\"reset\">Reset<\/button><\/div><div class=\"field is-checkbox hidden!\" id=\"field-auto-calc\"><input type=\"checkbox\" id=\"auto-calc\"><label for=\"auto-calc\">Calculate automatically<\/label><small>If enabled, the result will update automatically when you change any value.<\/small><\/div><div class=\"fieldset-result is-hidden\" aria-labelledby=\"result-title\" aria-live=\"polite\" role=\"region\"> <h3 class=\"result-title bg-gradient-to-r from-primary-50 to-gray-50 dark:from-primary-900 dark:to-gray-800\" id=\"result-title\"><span class=\"icon icon-s-pulse\" aria-hidden=\"true\"><\/span> Voltage Divider Results<\/h3><div class=\"result-box\"><div class=\"field-result\" id=\"output-1\"><span class=\"field-title\"><span>Output Voltage (Vout)<\/span><span class=\"result-term\">Vout<\/span><\/span><span class=\"field-value\" id=\"result-1\" data-unit=\"V\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result\" id=\"output-2\"><span class=\"field-title\"><span>Divider Ratio<\/span><span class=\"result-term\">Vout\/Vin<\/span><\/span><span class=\"field-value\" id=\"result-2\" data-unit=\"%\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result\" id=\"output-3\"><span class=\"field-title\"><span>Divider Current<\/span><span class=\"result-term\">I<\/span><\/span><span class=\"field-value\" id=\"result-3\" data-unit=\"mA\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result\" id=\"output-4\"><span class=\"field-title\"><span>Power in R1<\/span><span class=\"result-term\">P\u2081<\/span><\/span><span class=\"field-value\" id=\"result-4\" data-unit=\"mW\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result\" id=\"output-5\"><span class=\"field-title\"><span>Power in R2<\/span><span class=\"result-term\">P\u2082<\/span><\/span><span class=\"field-value\" id=\"result-5\" data-unit=\"mW\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result is-column\" id=\"output-6\"><span class=\"field-title\"><span>Loaded Output and Details<\/span><\/span><span class=\"field-value\" id=\"result-6\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result is-column\" id=\"output-7\"><span class=\"field-title\"><span>Standard Resistor Pairs<\/span><\/span><span class=\"field-value\" id=\"result-7\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><div class=\"field-result is-column\" id=\"output-8\"><span class=\"field-title\"><span>Divider Schematic<\/span><\/span><span class=\"field-value\" id=\"result-8\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><\/div><div class=\"result-actions\"><button type=\"button\" class=\"copy-link\"><svg viewBox=\"0 0 20 20\" fill=\"currentColor\" aria-hidden=\"true\"><path d=\"M12.232 4.232a2.5 2.5 0 0 1 3.536 3.536l-1.225 1.224a.75.75 0 0 0 1.061 1.06l1.224-1.224a4 4 0 0 0-5.656-5.656l-3 3a4 4 0 0 0 .225 5.865.75.75 0 0 0 .977-1.138 2.5 2.5 0 0 1-.142-3.667l3-3Z\"\/><path d=\"M11.603 7.963a.75.75 0 0 0-.977 1.138 2.5 2.5 0 0 1 .142 3.667l-3 3a2.5 2.5 0 0 1-3.536-3.536l1.225-1.224a.75.75 0 0 0-1.061-1.06l-1.224 1.224a4 4 0 1 0 5.656 5.656l3-3a4 4 0 0 0-.225-5.865Z\"\/><\/svg><span class=\"copy-link__text\">Copy link to this calculation<\/span><\/button><span class=\"sr-only\" role=\"status\" id=\"copy-link-status\"><\/span><\/div><\/div><a href=\"#respond\" class=\"hidden transition-opacity duration-300 opacity-0 w-50 text-sm justify-center items-center gap-2 px-4 py-2 rounded bg-gray-200 text-gray-700 hover:bg-gray-300\" id=\"leave-comment\"><span class=\"icon icon-comments\" aria-hidden=\"true\"><\/span>Leave a Comment<\/a><\/form><\/section><section id=\"calc-reactions\" class=\"not-prose hidden my-12 bg-gradient-to-r from-primary-50 to-gray-50 border border-indigo-100 rounded-xl px-6 py-4 shadow-sm\" data-post=\"67381\" aria-live=\"polite\" aria-labelledby=\"calc-reactions-title\"><p id=\"calc-reactions-title\" class=\"text-sm text-gray-500 text-center mb-2\">How did this result make you feel?<\/p><div role=\"group\" aria-labelledby=\"calc-reactions-title\" class=\"grid grid-cols-3 sm:flex sm:flex-row sm:justify-around gap-4 sm:items-center sm:flex-wrap\"><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"like\"><span class=\"reaction-count\" data-reaction-count=\"like\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude00 <\/span><span class=\"reaction-description font-medium\">Like <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"helpful\"><span class=\"reaction-count\" data-reaction-count=\"helpful\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\udca1 <\/span><span class=\"reaction-description font-medium\">Helpful <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"confused\"><span class=\"reaction-count\" data-reaction-count=\"confused\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude15 <\/span><span class=\"reaction-description font-medium\">Confused <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"disappointed\"><span class=\"reaction-count\" data-reaction-count=\"disappointed\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude1e <\/span><span class=\"reaction-description font-medium\">Disappointed <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"inaccurate\"><span class=\"reaction-count\" data-reaction-count=\"inaccurate\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\u274c <\/span><span class=\"reaction-description font-medium\">Inaccurate <\/span><\/button><\/div><div id=\"reaction-message\" class=\"hidden mt-8 rounded-md border border-primary-100 bg-white\/50 backdrop-blur-sm px-4 py-2 text-sm text-center shadow-sm\"><\/div><\/section><div class=\"calcdash-ad not-prose calcdash-ad--calc_result calcdash-ad--in-article\"><ins class=\"adsbygoogle\" style=\"display:block\" data-ad-client=\"ca-pub-1721569815777345\" data-ad-slot=\"6317458308\" data-ad-layout=\"in-article\" data-ad-format=\"fluid\"><\/ins><script>(adsbygoogle = window.adsbygoogle || []).push({});<\/script><\/div>\n<style id=\"wpcoderpro-inline-1\">.formula-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section class=\"formula-box\" aria-labelledby=\"formula-title\">\r\n\t<div id=\"formula-title\" class=\"not-prose font-display mb-4\"><span class=\"icon icon-formula\" aria-hidden=\"true\"><\/span><h2>Voltage Divider Formula<\/h2><\/div>\r\n\t<figure class=\"not-prose formula\">\r\n\t\t<figcaption class=\"formula-title\">Formula<\/figcaption>\r\n\t\t<div class=\"text-base text-gray-800\" id=\"formula\">\n\\[ V_{out} = V_{in} \\cdot \\frac{R_2}{R_1 + R_2} \\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(V_{out}\\) \u2014 voltage at the divider tap (V)<\/li>\n<li>\\(V_{in}\\) \u2014 supply voltage across the whole divider (V)<\/li>\n<li>\\(R_1\\) \u2014 resistor between \\(V_{in}\\) and the tap (&Omega;)<\/li>\n<li>\\(R_2\\) \u2014 resistor between the tap and ground (&Omega;)<\/li>\n<\/ul>\n<p>The formula states that the tap voltage is the fraction of \\(V_{in}\\) proportional to the lower resistor's share of the total resistance. Rearranged, it also solves the other unknowns: \\(V_{in} = V_{out}\\frac{R_1 + R_2}{R_2}\\), \\(R_1 = R_2\\left(\\frac{V_{in}}{V_{out}} - 1\\right)\\) and \\(R_2 = R_1\\frac{V_{out}}{V_{in} - V_{out}}\\).<\/p>\n<p>\r\n<\/section>\n<style id=\"wpcoderpro-inline-459\">.calculation-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section id=\"calculation\" class=\"calculation-box\" aria-labelledby=\"calculation-title\">\r\n\t<div id=\"calculation-title\" class=\"not-prose font-display\"><span class=\"icon icon-unordered-list\" aria-hidden=\"true\"><\/span><h2>Voltage Divider \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> a 12 V supply feeds a divider with R1 = 10 k&Omega; on top and R2 = 8.2 k&Omega; on the bottom (the calculator's default values). What is the output voltage?<\/p>\n<p>\\[ V_{out} = 12 \\cdot \\frac{8200}{10000 + 8200} = 12 \\cdot \\frac{8200}{18200} = 5.407 \\text{ V} \\]<\/p>\n<p>The divider ratio is \\( \\frac{8200}{18200} = 45.05\\% \\). The current through the chain is:<\/p>\n<p>\\[ I = \\frac{V_{in}}{R_1 + R_2} = \\frac{12}{18200} = 0.659 \\text{ mA} \\]<\/p>\n<p>so R1 dissipates \\( I^2 R_1 = 4.35 \\text{ mW} \\) and R2 dissipates \\( I^2 R_2 = 3.56 \\text{ mW} \\).<\/p>\n<p><strong>Result:<\/strong> Vout = 5.41 V at 45.05% of Vin, with 0.66 mA flowing through the divider.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to Use the Calculator<\/h2>\n<ol>\n<li>In <strong>Solve for<\/strong>, choose the unknown: <em>Vout from Vin, R1, R2<\/em>, <em>Vin from Vout, R1, R2<\/em>, <em>R1 from Vin, Vout, R2<\/em>, <em>R2 from Vin, Vout, R1<\/em>, or <em>Standard resistor pair (E-series)<\/em>. The calculator shows only the fields needed for your choice.<\/li>\n<li>Enter the known voltages in <strong>Input voltage (Vin)<\/strong> and <strong>Output voltage (Vout)<\/strong>, selecting V or mV in the unit dropdown.<\/li>\n<li>Enter the known resistances in <strong>Resistor R1 (top)<\/strong> and <strong>Resistor R2 (bottom)<\/strong>, choosing &Omega;, k&Omega; or M&Omega;. R1 sits between Vin and the tap; R2 sits between the tap and ground.<\/li>\n<li>Optionally set a <strong>Load resistance (RL)<\/strong> wired in parallel with R2 \u2014 for example an ADC input or bias network. Leave it at 0 for an unloaded divider.<\/li>\n<li>In the <em>Standard resistor pair<\/em> mode, enter the <strong>Target ratio (Vout\/Vin)<\/strong> (e.g. 0.45 for 45% of the supply) and pick an E-series under <strong>Resistor series<\/strong>: E12 (&plusmn;10%), E24 (&plusmn;5%) or E96 (&plusmn;1%).<\/li>\n<li>Read the results: output voltage, divider ratio, divider current, power dissipated in each resistor, the loaded-output analysis, and a live schematic of your divider.<\/li>\n<\/ol>\n<h2>What Is a Voltage Divider?<\/h2>\n<p>A voltage divider is two resistors in series across a supply. Because the same current flows through both, the supply voltage is split between them in proportion to their resistances, and the junction between them \u2014 the tap \u2014 sits at an intermediate voltage. It is one of the most common building blocks in electronics, used to scale a sensor signal into an ADC input range, set a transistor's bias point, shift the level of a signal, or read a potentiometer's position.<\/p>\n<p>The output is always a fixed <em>fraction<\/em> of the input, never more than the input: \\(V_{out}\/V_{in} = R_2\/(R_1 + R_2)\\) can only take values between 0 and 1. If you need a voltage higher than what a divider can give, or a stiff regulated supply, consider a regulator or a <a href=\"https:\/\/wpcalc.com\/en\/engineering\/zener-diode\/\">Zener diode circuit with its series resistor<\/a> instead.<\/p>\n<p>The choice of absolute resistor values is a trade-off. Large resistors waste little current, but the divider's output impedance (roughly \\(R_1 \\parallel R_2\\)) becomes high and the tap is easily pulled down by whatever it feeds. Small resistors make a stiffer tap but burn more current in the chain \u2014 the calculator's <em>Divider Current<\/em> and <em>Power in R1\/R2<\/em> fields let you check that the current budget and the resistors' power ratings are respected. A common starting point is a total chain resistance of 10 k&Omega; to 100 k&Omega;.<\/p>\n<p>When a load \\(R_L\\) is connected across R2, it forms a parallel combination \\(R_2 \\parallel R_L\\) that is smaller than R2 alone, so the tap voltage sags below the unloaded value. The calculator computes this loaded output; a widely used rule of thumb is to keep \\(R_L\\) at least ten times \\(R_2\\), which limits the sag to roughly 10%.<\/p>\n<h2>Assumptions, Limitations and Practical Tips<\/h2>\n<ul>\n<li><strong>DC or low-frequency only.<\/strong> The formula treats the resistors as ideal. At high frequencies, stray capacitance and inductance matter \u2014 see the <a href=\"https:\/\/wpcalc.com\/en\/engineering\/rc-time-constant\/\">RC time constant calculator<\/a> for the bandwidth of a divider feeding a capacitive load, or the <a href=\"https:\/\/wpcalc.com\/en\/engineering\/skin-depth\/\">skin depth calculator<\/a> for conductor behavior at high frequencies.<\/li>\n<li><strong>No current may be drawn from the tap.<\/strong> The unloaded formula assumes \\(R_L = \\infty\\). Any real load in parallel with R2 lowers the output; always check the loaded result before trusting the tap voltage.<\/li>\n<li><strong>The resistors load the source.<\/strong> The divider draws \\(I = V_{in}\/(R_1 + R_2)\\) continuously from the supply. In battery-powered devices, this quiescent current may dominate the power budget.<\/li>\n<li><strong>Tolerance shifts the ratio.<\/strong> Two &plusmn;5% resistors (E24) can move \\(V_{out}\\) by roughly twice that, so don't rely on a divider for precision without measuring or using E96 (&plusmn;1%) parts. The standard-pair finder reports each candidate pair's ratio error so you can see the nominal accuracy.<\/li>\n<li><strong>A divider is not a regulator.<\/strong> Every ripple or drift on \\(V_{in}\\) appears at the tap, scaled by the same ratio. If the input moves, so does the output.<\/li>\n<li><strong>Use it for sensing, not powering.<\/strong> Dividers are ideal as reference taps for high-impedance inputs like op-amp followers, comparators and ADCs. For driving real loads, follow the tap with a buffer or use a separate supply sized with the <a href=\"https:\/\/wpcalc.com\/en\/engineering\/ohms-law\/\">Ohm's law calculator<\/a>.<\/li>\n<li><strong>Alternative topologies.<\/strong> If you need a ratiometric measurement that rejects resistance drift, a <a href=\"https:\/\/wpcalc.com\/en\/engineering\/wheatstone-bridge\/\">Wheatstone bridge<\/a> is the classic solution.<\/li>\n<\/ul>\n<h2>Reference: Solving Each Unknown<\/h2>\n<table>\n<thead>\n<tr>\n<th>Unknown<\/th>\n<th>Rearranged formula<\/th>\n<th>What you enter<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Vout<\/td>\n<td>\\(V_{in} \\cdot \\frac{R_2}{R_1 + R_2}\\)<\/td>\n<td>Vin, R1, R2<\/td>\n<\/tr>\n<tr>\n<td>Vin<\/td>\n<td>\\(V_{out} \\cdot \\frac{R_1 + R_2}{R_2}\\)<\/td>\n<td>Vout, R1, R2<\/td>\n<\/tr>\n<tr>\n<td>R1<\/td>\n<td>\\(R_2 \\left(\\frac{V_{in}}{V_{out}} - 1\\right)\\)<\/td>\n<td>Vin, Vout, R2<\/td>\n<\/tr>\n<tr>\n<td>R2<\/td>\n<td>\\(R_1 \\cdot \\frac{V_{out}}{V_{in} - V_{out}}\\)<\/td>\n<td>Vin, Vout, R1<\/td>\n<\/tr>\n<tr>\n<td>Standard pair<\/td>\n<td>Closest \\(R_2\/(R_1 + R_2)\\) from the chosen E-series<\/td>\n<td>Vin, target ratio, series<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"excerpt":{"rendered":"<p>Calculate the output voltage of a resistive voltage divider, or solve for Vin, R1 or R2. Enter your values, add an optional load resistance, or find the closest standard E-series resistor pair for a target ratio.<\/p>\n","protected":false},"author":3168,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[4],"tags":[94],"class_list":["post-67381","post","type-post","status-publish","format-standard","hentry","category-engineering","tag-circuits"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/67381","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/users\/3168"}],"replies":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/comments?post=67381"}],"version-history":[{"count":1,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/67381\/revisions"}],"predecessor-version":[{"id":67382,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/67381\/revisions\/67382"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=67381"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=67381"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=67381"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}