{"id":55924,"date":"2015-10-24T15:52:59","date_gmt":"2015-10-24T13:52:59","guid":{"rendered":"http:\/\/wpcalc.com\/?p=55924"},"modified":"2026-09-28T09:12:48","modified_gmt":"2026-09-28T06:12:48","slug":"cubic-feet-per-minute","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/converters\/cubic-feet-per-minute\/","title":{"rendered":"CFM \u2013 Cubic Feet per Minute 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\">Airflow Volume (CFM, FPM, Area) Calculator<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"55924\" data-favorite-title=\"Cubic Feet per Minute (CFM)\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/converters\/cubic-feet-per-minute\/\" data-favorite-excerpt=\"Calculate airflow in cubic feet per minute (CFM) from air velocity in feet per minute (FPM) and cross-sectional area in square feet.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-volume\">\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\/cubic-feet-per-minute\/\" method=\"POST\" class=\"calculator\" id=\"calculator-55924\" data-post=\"55924\"><fieldset class=\"fieldset-input\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field\" id=\"input-1\"><label for=\"field-1\">Calculation Mode<\/label><div class=\"grid grid-cols-1\"><select id=\"field-1\" name=\"calculation_mode\"><option value=\"cfm\">Calculate CFM<\/option><option value=\"fpm\">Calculate FPM<\/option><option value=\"area\">Calculate Area<\/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\">FPM (Feet per Minute)<\/label><div class=\"term\">fpm<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"fpm_feet_per_minute\" id=\"field-2\" aria-describedby=\"calc-unit-2\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"0\" value=\"500\"\/><div class=\"unit\" id=\"calc-unit-2\">fpm<\/div><\/div><div class=\"field has-term\" id=\"input-3\"><label for=\"field-3\">Area<\/label><div class=\"term\">area<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"area\" id=\"field-3\" aria-describedby=\"calc-unit-3\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"0\" value=\"2\"\/><div class=\"unit\" id=\"calc-unit-3\">ft\u00b2<\/div><\/div><div class=\"field has-term\" id=\"input-4\" hidden><label for=\"field-4\">CFM<\/label><div class=\"term\">cfm<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"number\" name=\"cfm\" id=\"field-4\" aria-describedby=\"calc-unit-4\" step=\"any\" value=\"\"\/><div class=\"unit\" id=\"calc-unit-4\">cfm<\/div><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"55924\">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>Result<\/span><\/span><span class=\"field-value\" id=\"result-1\" 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><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=\"55924\" 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\">1<\/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\">1<\/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\">2<\/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>Cubic Feet per Minute (CFM) 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\\[ \\begin{aligned} \\text{CFM} &amp;= \\text{FPM} \\times \\text{Area} \\\\ \\text{FPM} &amp;= \\frac{\\text{CFM}}{\\text{Area}} \\\\ \\text{Area} &amp;= \\frac{\\text{CFM}}{\\text{FPM}} \\end{aligned} \\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(\\text{CFM}\\) \u2014 volumetric airflow in cubic feet per minute.<\/li>\n<li>\\(\\text{FPM}\\) \u2014 average air velocity through the opening in feet per minute.<\/li>\n<li>\\(\\text{Area}\\) \u2014 cross-sectional area of the opening in square feet.<\/li>\n<\/ul>\n<p>Airflow equals average velocity multiplied by the area the air passes through. The rearranged equations solve for velocity or area when CFM and the other value are known.<\/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>Cubic Feet per Minute (CFM) \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> air moves through a duct with a cross-sectional area of 2 ft\u00b2 at an average velocity of 500 fpm.<\/p>\n<p>\\[ \\text{CFM} = 500\\ \\text{ft\/min} \\times 2\\ \\text{ft}^2 = 1{,}000\\ \\text{ft}^3\/\\text{min} \\]<\/p>\n<p><strong>Result:<\/strong> the airflow is 1,000 cfm.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to use the calculator<\/h2>\n<ol>\n<li>Set <strong>Calculation Mode<\/strong> to <strong>Calculate CFM<\/strong>.<\/li>\n<li>Enter the average air velocity in <strong>FPM (Feet per Minute)<\/strong>.<\/li>\n<li>Enter the cross-sectional opening size in <strong>Area<\/strong>, measured in ft\u00b2.<\/li>\n<li>Read the airflow under <strong>Result<\/strong>, in cfm. The result is rounded to two decimal places.<\/li>\n<\/ol>\n<p>The <strong>Calculation Mode<\/strong> menu also lists <strong>Calculate FPM<\/strong> and <strong>Calculate Area<\/strong>. Both calculations require a known CFM value, but the current interface hides the <strong>CFM<\/strong> field. It also hides another required input in each of those modes. Consequently, the reverse modes may not produce a usable result from the visible fields. To work backward, use the rearranged equations in the formula block with your known values.<\/p>\n<h2>What CFM tells you about airflow<\/h2>\n<p>CFM is a volume flow rate: it describes how many cubic feet of air pass through a cross-section each minute. FPM describes speed, not volume. At the same average velocity, a larger opening carries more air; through the same opening, a higher average velocity carries more air. That is why both velocity and area are needed to calculate CFM.<\/p>\n<p>The area in this equation is the cross-section <em>perpendicular<\/em> to airflow, such as the open face of a duct or vent. It is not the floor area of a room. For a rectangular opening, multiply its inside width by its inside height. For a circular opening, use \\(\\text{Area}=\\pi d^2\/4\\), where \\(d\\) is the inside diameter. Measure dimensions in feet to obtain ft\u00b2; if dimensions are in inches, calculate the area in square inches and divide by 144.<\/p>\n<p>A calculated CFM is the flow through the opening at the velocity you entered. It does not, by itself, establish how much ventilation a room needs. Required airflow depends on the application and may be governed by occupancy, equipment specifications, ventilation standards, or local requirements. Likewise, an airflow measured at one duct section should not automatically be treated as the flow delivered at every outlet.<\/p>\n<h2>Measurement tips and limitations<\/h2>\n<ul>\n<li><strong>Use average velocity.<\/strong> Air often moves faster near the center of a duct than near its walls. A single spot reading may not represent the full cross-section; several measurements across the opening can give a better average.<\/li>\n<li><strong>Use the effective opening.<\/strong> For a duct, use its internal cross-sectional dimensions. A grille\u2019s outside dimensions may overstate the space air can pass through because the frame and blades occupy part of the opening.<\/li>\n<li><strong>Keep units consistent.<\/strong> The calculator expects fpm and ft\u00b2. If you measured a length in meters, convert it to feet before calculating an area in ft\u00b2. The <a href=\"https:\/\/wpcalc.com\/en\/converters\/meters-to-feet\/\">meters-to-feet converter<\/a> can help with that step.<\/li>\n<li><strong>Do not divide by zero.<\/strong> Calculating FPM requires an area greater than zero; calculating area requires an FPM greater than zero. Zero velocity or zero area gives zero CFM in the forward equation.<\/li>\n<li><strong>Allow for real-system losses.<\/strong> This equation relates velocity and area at the point of measurement. It does not predict fan performance or account for duct resistance, leaks, filters, or changes in air density. If you need to express a measured volume in another unit, use the <a href=\"https:\/\/wpcalc.com\/en\/converters\/volume\/\">volume unit converter<\/a>; remember that CFM is a rate, so the time unit must be converted as well.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Calculate airflow in cubic feet per minute (CFM) from air velocity in feet per minute (FPM) and cross-sectional area in square feet.<\/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":[40],"class_list":["post-55924","post","type-post","status-publish","format-standard","hentry","category-converters","tag-volume-units"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/55924","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=55924"}],"version-history":[{"count":2,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/55924\/revisions"}],"predecessor-version":[{"id":65253,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/55924\/revisions\/65253"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=55924"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=55924"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=55924"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}