{"id":65785,"date":"2026-09-30T11:28:26","date_gmt":"2026-09-30T08:28:26","guid":{"rendered":"https:\/\/wpcalc.com\/en\/?p=65785"},"modified":"2026-09-30T11:28:26","modified_gmt":"2026-09-30T08:28:26","slug":"air-conditioner-btu-calculator","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/life\/air-conditioner-btu-calculator\/","title":{"rendered":"Air Conditioner BTU 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\">Find the Right AC Size for Your Room<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"65785\" data-favorite-title=\"Air Conditioner BTU\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/life\/air-conditioner-btu-calculator\/\" data-favorite-excerpt=\"Estimate the cooling capacity an air conditioner needs for your room. Enter the room size, ceiling height, sun exposure, occupancy and appliance heat to get the result in BTU\/h and watts.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-eco-home\">\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\/life\/air-conditioner-btu-calculator\/\" method=\"POST\" class=\"calculator\" id=\"calculator-65785\" data-post=\"65785\"><fieldset class=\"fieldset-input is-2\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field has-term\" id=\"input-1\"><label for=\"field-1\">Room area (A)<\/label><div class=\"term\">A<\/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=\"room_area_a\" id=\"field-1\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"Area\" min=\"1\" value=\"20\"\/><div class=\"grid grid-cols-1\"><select id=\"field-2\" name=\"unit\" aria-label=\"Unit\"><option value=\"m2\" selected>m\u00b2<\/option><option value=\"ft2\">ft\u00b2<\/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><div class=\"field has-term\" id=\"input-2\"><label for=\"field-3\">Ceiling height (H)<\/label><div class=\"term\">H<\/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=\"ceiling_height_h\" id=\"field-3\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"Height\" min=\"1\" value=\"2.7\"\/><div class=\"grid grid-cols-1\"><select id=\"field-4\" name=\"unit\" aria-label=\"Unit\"><option value=\"m\" selected>m<\/option><option value=\"ft\">ft<\/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><div class=\"field\" id=\"input-3\"><label for=\"field-5\">Sun exposure<\/label><div class=\"grid grid-cols-1\"><select id=\"field-5\" name=\"sun_exposure\"><option value=\"0.9\">Heavily shaded<\/option><option value=\"1.0\" selected>Average<\/option><option value=\"1.1\">Very sunny<\/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-4\"><label for=\"field-6\">Number of people<\/label><input type=\"text\" name=\"number_of_people\" id=\"field-6\" aria-describedby=\"calc-info-6\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"People\" min=\"1\" value=\"2\"\/><small id=\"calc-info-6\">The base estimate already covers 2 people<\/small><\/div><div class=\"field is-checkbox is-single\" id=\"input-5\"><input type=\"checkbox\" id=\"field-7\" value=\"293\"\/><label for=\"field-7\">Kitchen or heat-producing appliances<\/label><\/div><div class=\"field\" id=\"input-6\"><label for=\"field-8\">Other equipment power<\/label><input type=\"text\" name=\"other_equipment_power\" id=\"field-8\" aria-describedby=\"calc-unit-8 calc-info-8\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"0\" min=\"0\" value=\"0\"\/><div class=\"unit\" id=\"calc-unit-8\">W<\/div><small id=\"calc-info-8\">Computers, TVs, ovens etc. \u2014 total heat output<\/small><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"65785\">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> Estimated Cooling Capacity<\/h3><div class=\"result-box\"><div class=\"field-result\" id=\"output-1\"><span class=\"field-title\"><span>Cooling capacity<\/span><\/span><span class=\"field-value\" id=\"result-1\" data-unit=\"BTU\/h\"><\/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>Cooling power<\/span><\/span><span class=\"field-value\" id=\"result-2\" data-unit=\"W\"><\/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=\"65785\" 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>Air Conditioner BTU 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\\[ P = A \\times H \\times q \\times k + 100\\,(n - 2) + P_{kitchen} + P_{equipment} \\]\n\\[ Q = P \\times 3.412142 \\]<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(P\\) \u2014 required cooling power (W)<\/li>\n<li>\\(A\\) \u2014 room floor area (m\u00b2)<\/li>\n<li>\\(H\\) \u2014 ceiling height (m)<\/li>\n<li>\\(q\\) \u2014 base cooling load, 40 W per m\u00b3 of room volume<\/li>\n<li>\\(k\\) \u2014 sun exposure factor: 0.9 for a heavily shaded room, 1.0 for average, 1.1 for a very sunny room<\/li>\n<li>\\(n\\) \u2014 number of people normally in the room<\/li>\n<li>\\(P_{kitchen}\\) \u2014 kitchen surcharge, 293 W (about 1000 BTU\/h) if the room contains a kitchen or heat-producing appliances<\/li>\n<li>\\(P_{equipment}\\) \u2014 total heat output of other equipment (W)<\/li>\n<li>\\(Q\\) \u2014 cooling capacity in BTU\/h (1 W = 3.412142 BTU\/h)<\/li>\n<\/ul>\n<p>The formula sizes the air conditioner from the room volume, corrects it for how much sun the room gets, and adds extra load for people and equipment beyond the base estimate.<\/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>Air Conditioner BTU \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> a living room of 20 m\u00b2 with a 2.7 m ceiling, average sun exposure, 2 people, no kitchen and no extra equipment.<\/p>\n<p>\\[ P = 20 \\times 2.7 \\times 40 \\times 1.0 = 2160\\ \\text{W} \\]<\/p>\n<p>\\[ Q = 2160 \\times 3.412142 \\approx 7370\\ \\text{BTU\/h} \\]<\/p>\n<p><strong>Result:<\/strong> about 7400 BTU\/h (2160 W). An AC unit rated at roughly 7000\u20138000 BTU\/h is appropriate for this room.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to Use the Calculator<\/h2>\n<ol>\n<li>Enter the <strong>Room area (A)<\/strong> and choose whether the value is in <strong>m\u00b2<\/strong> or <strong>ft\u00b2<\/strong>.<\/li>\n<li>Enter the <strong>Ceiling height (H)<\/strong> and select <strong>m<\/strong> or <strong>ft<\/strong>. Taller ceilings mean more air to cool, so this value matters.<\/li>\n<li>Pick the <strong>Sun exposure<\/strong> that best matches the room: heavily shaded, average, or very sunny (large south- or west-facing windows).<\/li>\n<li>Set the <strong>Number of people<\/strong> usually occupying the room. The base estimate already includes 2 people; each additional person adds about 100 W of heat.<\/li>\n<li>Tick <strong>Kitchen or heat-producing appliances<\/strong> if the room contains a kitchen area \u2014 this adds about 1000 BTU\/h.<\/li>\n<li>Enter the total wattage of <strong>Other equipment<\/strong> such as computers, TVs or ovens, or leave it at 0.<\/li>\n<li>Read the result: the estimated <strong>Cooling capacity<\/strong> in BTU\/h and the equivalent <strong>Cooling power<\/strong> in watts.<\/li>\n<\/ol>\n<h2>What Does BTU Mean for an Air Conditioner?<\/h2>\n<p>BTU stands for British Thermal Unit. One BTU is the amount of heat needed to raise the temperature of one pound of water by 1 \u00b0F. Air conditioner capacity is expressed in BTU per hour (BTU\/h) \u2014 how much heat the unit can remove from a room in one hour. A higher rating means more cooling power, and the right rating depends on the size and conditions of the room.<\/p>\n<p>An undersized unit will run constantly without ever reaching the set temperature, wearing itself out while barely cooling. An oversized unit is also a problem: it cools the air too quickly, short-cycling on and off, which wastes energy, fails to remove humidity properly and leaves the room feeling cold and damp. Matching the capacity to the actual load \u2014 as this calculator estimates \u2014 gives the best comfort and efficiency.<\/p>\n<p>The result is rounded to the nearest 100 BTU\/h. In practice, you should buy a unit with a nominal rating close to the estimate \u2014 typically the nearest standard size, such as 5000, 7000, 9000 or 12000 BTU\/h. A difference of a few hundred BTU\/h in either direction is not critical.<\/p>\n<h2>Assumptions and Limitations<\/h2>\n<ul>\n<li>The estimate uses a rule of thumb of 40 W of cooling per cubic metre of room volume, which suits typical residential rooms in a moderate climate with average insulation.<\/li>\n<li>It assumes a standard enclosed room with normal insulation, windows and doors. Very poor insulation, leaky windows, an attic directly above, or an extremely hot climate can all increase the required capacity.<\/li>\n<li>The model covers 2 people by default; only additional occupants add load. Kitchens add a fixed surcharge of about 1000 BTU\/h because cooking releases substantial heat.<\/li>\n<li>The calculator estimates the load for a single room. Central or multi-zone systems should be sized per zone and are best specified by an HVAC professional with a full Manual J load calculation.<\/li>\n<li>If the room borders a hot unconditioned space (garage, boiler room) or gets intense afternoon sun through large glass, consider choosing the next size up.<\/li>\n<\/ul>\n<h2>Practical Tips<\/h2>\n<p>When estimating equipment heat, add the typical power draw of devices that run for long periods: a desktop computer may contribute 100\u2013300 W, a gaming console 100\u2013200 W, a TV 50\u2013150 W. Devices that only run briefly (a kettle, a microwave) matter less. Laundry appliances in or near the room also release heat and moisture \u2014 if you are planning full household loads, the <a href=\"https:\/\/wpcalc.com\/en\/life\/laundry-load-weight-calculator\/\">Laundry Load Weight Calculator<\/a> can help you gauge how large they are.<\/p>\n<p>Remember that BTU\/h measures heat removal, not electrical consumption. A modern inverter AC removes 3\u20134 times more heat than the electricity it consumes, thanks to its high efficiency rating (SEER). So a 7000 BTU\/h unit does not draw 7000 W \u2014 it typically uses only 500\u2013800 W of electricity.<\/p>\n<p>Finally, if you are comparing window, portable and split units, check whether the quoted capacity is the original rating or a derated value adjusted for high outdoor temperatures \u2014 the difference can be 10\u201320% and may change which size you actually need.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Estimate the cooling capacity an air conditioner needs for your room. Enter the room size, ceiling height, sun exposure, occupancy and appliance heat to get the result in BTU\/h and watts.<\/p>\n","protected":false},"author":3168,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[6],"tags":[66],"class_list":["post-65785","post","type-post","status-publish","format-standard","hentry","category-life","tag-household"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/65785","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=65785"}],"version-history":[{"count":2,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/65785\/revisions"}],"predecessor-version":[{"id":67016,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/65785\/revisions\/67016"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=65785"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=65785"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=65785"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}