{"id":61889,"date":"2021-05-14T11:07:42","date_gmt":"2021-05-14T09:07:42","guid":{"rendered":"https:\/\/wpcalc.com\/?p=61889"},"modified":"2026-09-30T18:25:27","modified_gmt":"2026-09-30T15:25:27","slug":"maximum-floor-live-load-capacity","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/engineering\/maximum-floor-live-load-capacity\/","title":{"rendered":"Maximum Floor Live Load Capacity 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\">Calculate Maximum Live Load on Floor Structure<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"61889\" data-favorite-title=\"Maximum Floor Live Load Capacity\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/engineering\/maximum-floor-live-load-capacity\/\" data-favorite-excerpt=\"Estimate the maximum stationary live load a concrete slab-on-grade can carry. Enter allowable fiber stress, slab thickness, subgrade reaction modulus, and modulus of elasticity to get the capacity in psf.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-civil\">\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\/maximum-floor-live-load-capacity\/\" method=\"POST\" class=\"calculator\" id=\"calculator-61889\" data-post=\"61889\"><fieldset class=\"fieldset-input\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field has-term\" id=\"input-1\"><label for=\"field-1\">Allowable extreme fiber stress in tension<\/label><div class=\"term\">s<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"number\" name=\"allowable_extreme_fiber_stress_in_tension\" id=\"field-1\" aria-describedby=\"calc-unit-1\" step=\"0.01\" value=\"650\"\/><div class=\"unit\" id=\"calc-unit-1\">psi<\/div><\/div><div class=\"field has-term\" id=\"input-2\"><label for=\"field-2\">Thickness of slab<\/label><div class=\"term\">h<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"number\" name=\"thickness_of_slab\" id=\"field-2\" aria-describedby=\"calc-unit-2\" step=\"0.01\" value=\"6\"\/><div class=\"unit\" id=\"calc-unit-2\">in<\/div><\/div><div class=\"field has-term\" id=\"input-3\"><label for=\"field-3\">Modulus of subgrade reaction<\/label><div class=\"term\">k<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"number\" name=\"modulus_of_subgrade_reaction\" id=\"field-3\" aria-describedby=\"calc-unit-3\" step=\"0.01\" value=\"100\"\/><div class=\"unit\" id=\"calc-unit-3\">pci<\/div><\/div><div class=\"field has-term\" id=\"input-4\"><label for=\"field-4\">Modulus of elasticity<\/label><div class=\"term\">E<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"number\" name=\"modulus_of_elasticity\" id=\"field-4\" aria-describedby=\"calc-unit-4\" step=\"0.01\" value=\"4000000\"\/><div class=\"unit\" id=\"calc-unit-4\">psi<\/div><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"61889\">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>Maximum allowable stationary live load<\/span><span class=\"result-term\">w<\/span><\/span><span class=\"field-value\" id=\"result-1\" data-unit=\"psf\"><\/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=\"61889\" 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>Maximum Floor Live Load Capacity 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\\[ w = 257.876 \\cdot s \\cdot \\sqrt{ \\frac{k \\, h}{E} } \\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(w\\) \u2014 maximum allowable stationary live load (psf, pounds per square foot)<\/li>\n<li>\\(s\\) \u2014 allowable extreme fiber stress in tension (psi)<\/li>\n<li>\\(h\\) \u2014 thickness of the slab (in)<\/li>\n<li>\\(k\\) \u2014 modulus of subgrade reaction (pci, pounds per cubic inch)<\/li>\n<li>\\(E\\) \u2014 modulus of elasticity of the slab material (psi)<\/li>\n<\/ul>\n<p>This empirical formula, widely used for concrete slabs on grade, estimates the uniformly distributed stationary live load a slab can support before the bending stress in the slab reaches the allowable tension limit. It combines the strength of the concrete (\\(s\\), \\(E\\)), the geometry of the slab (\\(h\\)), and the stiffness of the supporting soil (\\(k\\)).<\/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>Maximum Floor Live Load Capacity \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> a 6-inch concrete slab on grade rests on soil with a modulus of subgrade reaction of 100 pci. The concrete has an allowable extreme fiber stress in tension of 650 psi and a modulus of elasticity of 4,000,000 psi. What stationary live load can the floor carry?<\/p>\n<p>\\[ \\frac{k \\, h}{E} = \\frac{100 \\times 6}{4{,}000{,}000} = 0.00015 \\]<\/p>\n<p>\\[ w = 257.876 \\times 650 \\times \\sqrt{0.00015} \\approx 2052.91 \\text{ psf} \\]<\/p>\n<p><strong>Result:<\/strong> the maximum allowable stationary live load is approximately <strong>2052.91 psf<\/strong>, far above the 40\u2013125 psf typically required for residential and light commercial floors.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to Use the Calculator<\/h2>\n<ol>\n<li>Enter the <strong>Allowable extreme fiber stress in tension<\/strong> of the slab material in psi (about 650 psi is common for plain concrete; check your mix design or specification).<\/li>\n<li>Enter the <strong>Thickness of slab<\/strong> in inches \u2014 measure the full slab depth, not the wear surface or topping.<\/li>\n<li>Enter the <strong>Modulus of subgrade reaction<\/strong> in pci. If you do not have a plate load test result, use a typical value for your soil type (see the table below).<\/li>\n<li>Enter the <strong>Modulus of elasticity<\/strong> of the concrete in psi (typically 3,000,000\u20135,000,000 psi, with 4,000,000 psi a common assumption for normal-weight concrete).<\/li>\n<li>Read the <strong>Maximum allowable stationary live load<\/strong> in psf and compare it with the live load required by your building code.<\/li>\n<\/ol>\n<h2>What Is Floor Live Load Capacity?<\/h2>\n<p>Live load is the weight a floor must carry from things that move or change over time: people, furniture, stored goods, and equipment. It contrasts with dead load, which is the permanent weight of the structure itself. Building codes prescribe minimum live loads \u2014 commonly 40 psf for residential rooms, 50\u201380 psf for offices and classrooms, and 125 psf or more for storage and light industrial use.<\/p>\n<p>A slab on grade does not behave like a suspended beam-and-joist floor. It distributes loads through its own stiffness into the soil beneath it, so its capacity depends on how stiff the soil is (the modulus of subgrade reaction \\(k\\)), how thick the slab is (\\(h\\)), and how strong the concrete is (\\(s\\) and \\(E\\)). The formula used here captures that interaction: thicker slabs and stiffer subgrades both increase the allowable load, roughly with the square root of their product.<\/p>\n<p>The result, \\(w\\), is the stationary (uniformly distributed) live load the slab can carry without the tensile stress in the bottom of the slab exceeding the allowable limit. If the calculated capacity is comfortably above the code-required live load, the slab design is adequate; if it falls short, the slab must be thickened, the concrete strengthened, or the subgrade improved through compaction or a granular base.<\/p>\n<h2>Typical Modulus of Subgrade Reaction Values<\/h2>\n<table>\n<thead>\n<tr>\n<th>Soil \/ base condition<\/th>\n<th>Approximate \\(k\\) (pci)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Very soft clay or loose fine sand<\/td>\n<td>50\u201375<\/td>\n<\/tr>\n<tr>\n<td>Loose sand and gravel<\/td>\n<td>100\u2013150<\/td>\n<\/tr>\n<tr>\n<td>Medium-dense sand and gravel<\/td>\n<td>150\u2013250<\/td>\n<\/tr>\n<tr>\n<td>Dense sand and gravel \/ stiff clay<\/td>\n<td>250\u2013400<\/td>\n<\/tr>\n<tr>\n<td>Well-compacted granular base<\/td>\n<td>300\u2013500<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Because capacity scales with \\(\\sqrt{k}\\), improving compaction can meaningfully raise the allowable load \u2014 but only a plate load test gives a reliable \\(k\\) for a specific site.<\/p>\n<h2>Assumptions and Limitations<\/h2>\n<ul>\n<li>The formula applies to <strong>plain (unreinforced or lightly reinforced) concrete slabs on grade<\/strong> carrying a stationary, uniformly distributed live load. It is not valid for suspended slabs, elevated floors, or structural framed systems.<\/li>\n<li><strong>Concentrated loads<\/strong> \u2014 rack legs, machine feet, forklift wheels \u2014 are far more severe than the same weight spread evenly, and they require a separate point-load analysis.<\/li>\n<li>The result is an <strong>empirical estimate<\/strong>, not a substitute for a full design to ACI 360, TR 34, or similar slab-on-grade standards, especially for heavy industrial floors.<\/li>\n<li>Long-term effects \u2014 fatigue, shrinkage cracking, moisture changes in the subgrade, and edge or joint conditions \u2014 are not accounted for and can reduce the practical capacity.<\/li>\n<li>Always keep the units exactly as labeled (psi, inches, pci); mixing metric and imperial values will produce meaningless results.<\/li>\n<\/ul>\n<p>For companion calculations on the same project, see the <a href=\"https:\/\/wpcalc.com\/en\/engineering\/concrete-slab-maximum-wall-load\/\">concrete slab maximum wall load calculator<\/a>, the <a href=\"https:\/\/wpcalc.com\/en\/engineering\/concrete-slab-maximum-length-calculator\/\">concrete slab maximum length calculator<\/a>, and the <a href=\"https:\/\/wpcalc.com\/en\/engineering\/concrete-slab-pour-volume\/\">concrete slab pour volume calculator<\/a> to plan the pour itself.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Estimate the maximum stationary live load a concrete slab-on-grade can carry. Enter allowable fiber stress, slab thickness, subgrade reaction modulus, and modulus of elasticity to get the capacity in psf.<\/p>\n","protected":false},"author":70,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[4],"tags":[19],"class_list":["post-61889","post","type-post","status-publish","format-standard","hentry","category-engineering","tag-civil"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/61889","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=61889"}],"version-history":[{"count":2,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/61889\/revisions"}],"predecessor-version":[{"id":65987,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/61889\/revisions\/65987"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=61889"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=61889"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=61889"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}