{"id":55858,"date":"2015-10-24T16:03:24","date_gmt":"2015-10-24T14:03:24","guid":{"rendered":"http:\/\/wpcalc.com\/?p=55858"},"modified":"2026-09-28T09:25:45","modified_gmt":"2026-09-28T06:25:45","slug":"light-luminance","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/converters\/light-luminance\/","title":{"rendered":"Light Luminance Converter"},"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\">Convert Luminance Between Units<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"55858\" data-favorite-title=\"Light Luminance\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/converters\/light-luminance\/\" data-favorite-excerpt=\"Convert luminance between cd\/m\u00b2, nits, foot-lamberts, stilbs, and other units. Enter a luminance value, then choose the From unit and To unit.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-physic\">\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\/converters\/light-luminance\/\" method=\"POST\" class=\"calculator\" id=\"calculator-55858\" data-post=\"55858\"><fieldset class=\"fieldset-input\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field is-single\" id=\"input-1\"><label for=\"field-1\">Luminance value<\/label><input type=\"text\" name=\"luminance_value\" id=\"field-1\" aria-describedby=\"calc-unit-1 calc-info-1\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"0\" value=\"250\"\/><div class=\"unit\" id=\"calc-unit-1\"><\/div><small id=\"calc-info-1\">Enter the luminance value to convert<\/small><\/div><div class=\"field\" id=\"input-2\"><label for=\"field-2\">From unit<\/label><div class=\"grid grid-cols-1\"><select id=\"field-2\" name=\"from_unit\"><option value=\"cd\/m\u00b2\">Candela per square meter (cd\/m\u00b2)<\/option><option value=\"cd\/cm\u00b2\">Candela per square centimeter (cd\/cm\u00b2)<\/option><option value=\"cd\/ft\u00b2\">Candela per square foot (cd\/ft\u00b2)<\/option><option value=\"cd\/in\u00b2\">Candela per square inch (cd\/in\u00b2)<\/option><option value=\"nt\">Nit (nt)<\/option><option value=\"sb\">Stilb (sb)<\/option><option value=\"asb\">Apostilb (asb)<\/option><option value=\"lambert\">Lambert<\/option><option value=\"fL\">Foot-lambert (fL)<\/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\" id=\"input-3\"><label for=\"field-3\">To unit<\/label><div class=\"grid grid-cols-1\"><select id=\"field-3\" name=\"to_unit\"><option value=\"cd\/m\u00b2\">Candela per square meter (cd\/m\u00b2)<\/option><option value=\"cd\/cm\u00b2\">Candela per square centimeter (cd\/cm\u00b2)<\/option><option value=\"cd\/ft\u00b2\">Candela per square foot (cd\/ft\u00b2)<\/option><option value=\"cd\/in\u00b2\">Candela per square inch (cd\/in\u00b2)<\/option><option value=\"nt\">Nit (nt)<\/option><option value=\"sb\">Stilb (sb)<\/option><option value=\"asb\">Apostilb (asb)<\/option><option value=\"lambert\">Lambert<\/option><option value=\"fL\">Foot-lambert (fL)<\/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=\"55858\">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> Your Results<\/h3><div class=\"result-box\"><div class=\"field-result\" id=\"output-1\"><span class=\"field-title\"><span>Converted Luminance<\/span><\/span><span class=\"field-value\" id=\"result-1\"><\/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=\"55858\" 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>Light Luminance 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\\[L_{\\mathrm{to}}=L_{\\mathrm{from}}\\times\\frac{F_{\\mathrm{from}}}{F_{\\mathrm{to}}}\\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(L_{\\mathrm{from}}\\) \u2014 the entered luminance value in the selected From unit<\/li>\n<li>\\(L_{\\mathrm{to}}\\) \u2014 the converted value in the selected To unit<\/li>\n<li>\\(F_{\\mathrm{from}}\\) and \\(F_{\\mathrm{to}}\\) \u2014 the number of candela per square meter (cd\/m\u00b2) in one of each respective unit<\/li>\n<\/ul>\n<p>The calculator first expresses the entered value in cd\/m\u00b2, then divides by the factor for the destination unit. A nit has the same value as one cd\/m\u00b2, so converting between those two units does not change the number.<\/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>Light Luminance \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> Convert the default value of 250 cd\/m\u00b2 to foot-lamberts (fL). The calculator uses 1 fL = 3.4262591 cd\/m\u00b2.<\/p>\n<p>\\[L_{\\mathrm{fL}}=250\\times\\frac{1}{3.4262591}=72.965877\\ \\mathrm{fL}\\]<\/p>\n<p><strong>Result:<\/strong> 250 cd\/m\u00b2 is approximately 72.965877 fL.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to use the calculator<\/h2>\n<ol>\n<li>Enter a nonnegative number in <strong>Luminance value<\/strong>. The default is 250.<\/li>\n<li>Choose the unit of that number in <strong>From unit<\/strong>. The default is candela per square meter (cd\/m\u00b2).<\/li>\n<li>Choose the unit you need in <strong>To unit<\/strong>. The default is foot-lambert (fL).<\/li>\n<li>Read <strong>Converted Luminance<\/strong>. The result includes the selected destination unit and is displayed to no more than six decimal places.<\/li>\n<\/ol>\n<p>You can reverse the selections to convert in the other direction. If both menus use the same unit, the numerical value stays the same.<\/p>\n<h2>What luminance means<\/h2>\n<p>Luminance describes how much luminous intensity a surface emits, transmits, or reflects in a particular direction per unit of projected area. Its SI unit is candela per square meter (cd\/m\u00b2), commonly called a <strong>nit<\/strong>. Because direction and projected area matter, luminance is useful for describing displays, illuminated signs, and other surfaces viewed from a specified direction.<\/p>\n<p>A larger luminance value means more light intensity per projected area in that direction; it does not, by itself, say how bright an object will look to a person. Perceived brightness also depends on surrounding light, contrast, adaptation, and viewing conditions. Unit conversion changes only the way a measured or specified luminance is written\u2014it does not adjust for those conditions.<\/p>\n<p>Luminance is not the same as <a href=\"https:\/\/wpcalc.com\/en\/converters\/light-illumination\/\">illumination<\/a>, which describes light arriving at a surface, or <a href=\"https:\/\/wpcalc.com\/en\/converters\/luminous-intensity\/\">luminous intensity<\/a>, which describes light in a particular direction without dividing by apparent area. Keeping these quantities separate is important when comparing a screen specification with a measurement of light falling on a desk or wall.<\/p>\n<p>Foot-lamberts are often encountered in projected-image and cinema specifications, while nits are common in display specifications. Converting between them makes numerical comparisons possible, provided the specifications refer to comparable measurement conditions. For example, 250 nits and 250 cd\/m\u00b2 describe the same luminance, whereas 250 fL describes a substantially higher luminance.<\/p>\n<h2>Conversion factors and practical limits<\/h2>\n<p>The calculator uses cd\/m\u00b2 as an intermediate unit. The following factors show how many cd\/m\u00b2 correspond to one unit as implemented by this converter:<\/p>\n<table>\n<thead>\n<tr>\n<th>Unit<\/th>\n<th>cd\/m\u00b2 per unit<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Candela per square meter (cd\/m\u00b2)<\/td>\n<td>1<\/td>\n<\/tr>\n<tr>\n<td>Nit (nt)<\/td>\n<td>1<\/td>\n<\/tr>\n<tr>\n<td>Candela per square centimeter (cd\/cm\u00b2)<\/td>\n<td>10,000<\/td>\n<\/tr>\n<tr>\n<td>Candela per square foot (cd\/ft\u00b2)<\/td>\n<td>10.76391<\/td>\n<\/tr>\n<tr>\n<td>Candela per square inch (cd\/in\u00b2)<\/td>\n<td>1550.0031<\/td>\n<\/tr>\n<tr>\n<td>Stilb (sb)<\/td>\n<td>10,000<\/td>\n<\/tr>\n<tr>\n<td>Apostilb (asb)<\/td>\n<td>0.3183<\/td>\n<\/tr>\n<tr>\n<td>Lambert<\/td>\n<td>3183.0988618<\/td>\n<\/tr>\n<tr>\n<td>Foot-lambert (fL)<\/td>\n<td>3.4262591<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Some factors are rounded in the calculator, particularly the apostilb factor. Results can therefore differ slightly from conversions made with more precise constants. The displayed result is also rounded to six decimal places; a displayed zero after conversion can represent a very small, nonzero value.<\/p>\n<p>Use a luminance measurement or specification as the input, not a value in lumens, lux, or watts. Those describe different quantities and cannot be converted to luminance from a unit choice alone. If you are starting with luminous flux and electrical power instead, the <a href=\"https:\/\/wpcalc.com\/en\/converters\/lumens-to-watts\/\">lumens to watts converter<\/a> addresses that separate relationship.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Convert luminance between cd\/m\u00b2, nits, foot-lamberts, stilbs, and other units. Enter a luminance value, then choose the From unit and To unit.<\/p>\n","protected":false},"author":70,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[3],"tags":[34],"class_list":["post-55858","post","type-post","status-publish","format-standard","hentry","category-converters","tag-physics-units"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/55858","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\/70"}],"replies":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/comments?post=55858"}],"version-history":[{"count":2,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/55858\/revisions"}],"predecessor-version":[{"id":65284,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/55858\/revisions\/65284"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=55858"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=55858"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=55858"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}