{"id":66769,"date":"2026-10-13T08:58:03","date_gmt":"2026-10-13T05:58:03","guid":{"rendered":"https:\/\/wpcalc.com\/en\/?p=66769"},"modified":"2026-10-13T08:58:03","modified_gmt":"2026-10-13T05:58:03","slug":"pressure-altitude-calculator","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/converters\/pressure-altitude-calculator\/","title":{"rendered":"Pressure Altitude 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\">Estimate Altitude from a Barometric Pressure Reading<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"66769\" data-favorite-title=\"Pressure Altitude\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/converters\/pressure-altitude-calculator\/\" data-favorite-excerpt=\"Enter a barometric pressure reading and a reference (sea-level) pressure to find the corresponding pressure altitude in feet, metres, and flight levels, based on the international standard atmosphere.\" 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\/pressure-altitude-calculator\/\" method=\"POST\" class=\"calculator\" id=\"calculator-66769\" data-post=\"66769\"><fieldset class=\"fieldset-input is-1\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field has-term\" id=\"input-1\"><label for=\"field-1\">Atmospheric pressure (p)<\/label><div class=\"term\">p<\/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=\"atmospheric_pressure_p\" id=\"field-1\" aria-describedby=\"calc-info-1\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 1000\" min=\"0\" value=\"1000\"\/><div class=\"grid grid-cols-1\"><select id=\"field-2\" name=\"unit\" aria-label=\"Unit\"><option value=\"hpa\" selected>hPa (mbar)<\/option><option value=\"inhg\">inHg<\/option><option value=\"kpa\">kPa<\/option><option value=\"mmhg\">mmHg<\/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-1\">Barometric pressure measured at the site (station pressure, not corrected to sea level).<\/small><\/div><div class=\"field has-term\" id=\"input-2\"><label for=\"field-3\">Reference pressure (p\u2080)<\/label><div class=\"term\">p\u2080<\/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=\"reference_pressure_p\" id=\"field-3\" aria-describedby=\"calc-info-3\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"e.g. 1013.25\" min=\"0\" value=\"1013.25\"\/><div class=\"grid grid-cols-1\"><select id=\"field-4\" name=\"unit\" aria-label=\"Unit\"><option value=\"hpa\" selected>hPa (mbar)<\/option><option value=\"inhg\">inHg<\/option><option value=\"kpa\">kPa<\/option><option value=\"mmhg\">mmHg<\/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-3\">Sea-level pressure of the reference atmosphere. Leave at 1013.25 hPa (29.92 inHg) for the international standard atmosphere.<\/small><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"66769\">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> Pressure Altitude Results<\/h3><div class=\"result-box\"><div class=\"field-result is-column\" id=\"output-1\"><span class=\"field-title\"><span>Pressure altitude<\/span><span class=\"result-term\">PA<\/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 class=\"field-result is-column\" id=\"output-2\"><span class=\"field-title\"><span>Standard atmosphere details<\/span><\/span><span class=\"field-value\" id=\"result-2\"><\/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=\"66769\" 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>Pressure Altitude 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\\[ h = 44330.77 \\times \\left[ 1 - \\left( \\frac{p}{p_0} \\right)^{0.190263} \\right] \\]<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(h\\) \u2014 pressure altitude (m)<\/li>\n<li>\\(p\\) \u2014 measured atmospheric (station) pressure<\/li>\n<li>\\(p_0\\) \u2014 reference sea-level pressure (1013.25 hPa \/ 29.92 inHg for the standard atmosphere)<\/li>\n<\/ul>\n<p>This is the inverse of the barometric pressure law of the International Standard Atmosphere (ISA). It converts a pressure reading into the altitude at which that pressure would occur in the ISA, valid in the troposphere (below 11 km). Above the tropopause the calculator switches to the isothermal stratosphere layer at \u221256.5 \u00b0C:<\/p>\n<p>\\[ h = 11000 + 6341.62 \\times \\ln\\!\\left( \\frac{226.32}{p} \\right) \\quad \\text{(m, with } p \\text{ in hPa)} \\]\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>Pressure Altitude \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> a barometer at a weather station reads 1000 hPa, and you use the standard reference pressure of 1013.25 hPa.<\/p>\n<p>\\[ h = 44330.77 \\times \\left[ 1 - \\left( \\frac{1000}{1013.25} \\right)^{0.190263} \\right] \\]<\/p>\n<p>\\[ h = 44330.77 \\times \\left( 1 - 0.99750 \\right) \\approx 110.9 \\text{ m} \\approx 364 \\text{ ft} \\]<\/p>\n<p><strong>Result:<\/strong> the pressure altitude is about <strong>111 m (364 ft)<\/strong> above the reference datum. The ISA temperature at that level is \\( 15 - 0.0065 \\times 110.9 \\approx 14.3\\ \\text{\u00b0C} \\).<\/p>\n<p>\n\r\n<\/section>\n<h2>How to Use the Pressure Altitude Calculator<\/h2>\n<ol>\n<li>Enter the <strong>Atmospheric pressure (p)<\/strong> measured at your site. This must be the actual station pressure, not a value corrected to sea level.<\/li>\n<li>Choose the unit for this reading: hPa (mbar), inHg, kPa, or mmHg.<\/li>\n<li>Enter the <strong>Reference pressure (p\u2080)<\/strong>. Leave it at 1013.25 hPa (29.92 inHg) to use the international standard atmosphere, or enter the current sea-level pressure for your region if you know it.<\/li>\n<li>Set the unit for the reference pressure \u2014 it can differ from the unit of the first field.<\/li>\n<li>Read the results: the pressure altitude in feet, metres, kilometres, and as a flight level, plus standard-atmosphere details such as the pressure ratio and ISA temperature.<\/li>\n<\/ol>\n<h2>What Is Pressure Altitude?<\/h2>\n<p>Pressure altitude is the altitude in the International Standard Atmosphere at which a given pressure occurs. In other words, it answers the question: \"In the standard atmosphere, how high would I have to climb for the pressure to drop to the value I just measured?\" Because the atmosphere thins predictably with height, a barometric reading can be turned back into an altitude using the formula above.<\/p>\n<p>Pressure altitude matters chiefly in aviation. Aircraft altimeters are essentially barometers calibrated to the standard atmosphere: when the pilot sets 29.92 inHg (1013 hPa) on the altimeter, the instrument displays pressure altitude directly. Above the transition altitude, all aircraft fly with this same setting, so everyone's altimeter reads against a common reference \u2014 this is the basis of flight levels. Pressure altitude is also the starting point for computing density altitude, which aircraft performance tables rely on.<\/p>\n<p>Outside aviation, hikers, meteorologists, and drone operators use pressure altitude to estimate elevation from a barometer or pressure sensor \u2014 provided the reading is the true station pressure and a suitable reference pressure is used. The result can also come out negative: if the measured pressure is higher than the reference pressure, the level lies below the reference datum (below sea level in the standard atmosphere).<\/p>\n<p>Note that pressure altitude depends <em>only<\/em> on pressure \u2014 not on temperature or humidity. A hot, humid day and a cold, dry day at the same pressure give the same pressure altitude, even though the air density differs substantially.<\/p>\n<h2>Accuracy, Assumptions and Practical Tips<\/h2>\n<ul>\n<li><strong>Use station pressure.<\/strong> Weather reports usually quote pressure corrected to sea level (QNH). Feeding a sea-level-corrected value into the calculator will make the pressure altitude come out far too low \u2014 often below zero. If you only have the sea-level pressure and know your approximate elevation, correct it first.<\/li>\n<li><strong>The reference pressure matters.<\/strong> With the standard 1013.25 hPa you get the ISA pressure altitude. For a more realistic local estimate, use the current regional sea-level pressure (QNH) as the reference; then the result approximates your true elevation.<\/li>\n<li><strong>Layer limits.<\/strong> The troposphere formula is exact for the ISA only below 11 km; above that, the isothermal stratosphere layer is used, and results above 20 km are rough estimates.<\/li>\n<li><strong>Weather changes shift the result.<\/strong> Pressure systems moving through an area change station pressure by tens of hectopascals, which corresponds to hundreds of feet of pressure altitude. A reading taken during a low-pressure system will indicate a higher pressure altitude than the same physical spot under high pressure.<\/li>\n<li><strong>Pressure altitude is not density altitude.<\/strong> For aircraft take-off performance you also need temperature (and humidity) effects \u2014 pressure altitude alone is not the whole story.<\/li>\n<\/ul>\n<h2>Related Calculators<\/h2>\n<p>If you are working with other atmospheric conditions, you may also find our <a href=\"https:\/\/wpcalc.com\/en\/converters\/dew-point-calculator\/\">Dew Point Calculator<\/a>, <a href=\"https:\/\/wpcalc.com\/en\/converters\/heat-index-calculator\/\">Heat Index Calculator<\/a> and <a href=\"https:\/\/wpcalc.com\/en\/converters\/wind-chill-calculator\/\">Wind Chill Calculator<\/a> useful for describing the weather at the altitude you just calculated.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Enter a barometric pressure reading and a reference (sea-level) pressure to find the corresponding pressure altitude in feet, metres, and flight levels, based on the international standard atmosphere.<\/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":[3],"tags":[34],"class_list":["post-66769","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\/66769","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=66769"}],"version-history":[{"count":2,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66769\/revisions"}],"predecessor-version":[{"id":67052,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/66769\/revisions\/67052"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=66769"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=66769"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=66769"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}