{"id":57732,"date":"2016-03-18T11:32:19","date_gmt":"2016-03-18T09:32:19","guid":{"rendered":"http:\/\/wpcalc.com\/?p=57732"},"modified":"2026-09-28T13:53:04","modified_gmt":"2026-09-28T10:53:04","slug":"gestational-age","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/pregnancy-baby\/gestational-age\/","title":{"rendered":"Gestational Age 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 Pregnancy Age by Last Menstrual Period<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"57732\" data-favorite-title=\"Gestational Age Calculator (AOG)\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/pregnancy-baby\/gestational-age\/\" data-favorite-excerpt=\"Estimate gestational age in weeks and days and an expected delivery date. Enter the first day of your last menstrual period and your usual cycle length.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-embryo\">\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\/pregnancy-baby\/gestational-age\/\" method=\"POST\" class=\"calculator\" id=\"calculator-57732\" data-post=\"57732\"><fieldset class=\"fieldset-input\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field\" id=\"input-1\"><label for=\"field-1\">Last menstrual period<\/label><input type=\"date\" name=\"last_menstrual_period\" id=\"field-1\" step=\"any\" value=\"2026-11-12\"\/><\/div><div class=\"field\" id=\"input-2\"><label for=\"field-2\">Cycle Length<\/label><input type=\"text\" name=\"cycle_length\" id=\"field-2\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"20\" max=\"45\" value=\"28\"\/><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"57732\">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>Estimated Date of Delivery<\/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\" id=\"output-2\"><span class=\"field-title\"><span>Gestational age:<\/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 class=\"field-result\" id=\"output-3\"><span class=\"field-title\"><span>Weeks<\/span><\/span><span class=\"field-value\" id=\"result-3\"><\/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-4\"><span class=\"field-title\"><span>Days<\/span><\/span><span class=\"field-value\" id=\"result-4\"><\/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=\"57732\" 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\">3<\/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\">1<\/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\">1<\/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\">2<\/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>Gestational Age 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}L_a &amp;= L+(C-28)\\text{ days}\\\\D &amp;= \\text{days from }L_a\\text{ to today}\\\\W &amp;= \\left\\lfloor D\/7\\right\\rfloor,\\qquad R=D-7W\\\\E &amp;= L_a+280\\text{ days}\\end{aligned}\\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(L\\) \u2014 first day of the last menstrual period.<\/li>\n<li>\\(C\\) \u2014 usual cycle length in days; 28 is the calculator\u2019s reference length.<\/li>\n<li>\\(L_a\\) \u2014 cycle-adjusted starting date.<\/li>\n<li>\\(D\\) \u2014 elapsed days since \\(L_a\\); \\(W\\) and \\(R\\) are completed weeks and remaining days.<\/li>\n<li>\\(E\\) \u2014 estimated date of delivery.<\/li>\n<\/ul>\n<p>The calculator shifts the starting date by the difference between your cycle length and 28 days. It then expresses the elapsed time as weeks and days and adds 280 days to the adjusted date for the delivery 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>Gestational Age \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> The first day of your last menstrual period was July 6, 2026, and your usual cycle length is 28 days. Calculate your gestational age on September 28, 2026.<\/p>\n<p>\\[L_a=\\text{July 6, 2026}+(28-28)\\text{ days}=\\text{July 6, 2026}\\]<\/p>\n<p>\\[D=84\\text{ days},\\qquad W=84\\div7=12,\\qquad R=0\\text{ days}\\]<\/p>\n<p>\\[E=\\text{July 6, 2026}+280\\text{ days}=\\text{April 12, 2027}\\]<\/p>\n<p><strong>Result:<\/strong> The gestational age is 12 weeks and 0 days on September 28, 2026, and the estimated date of delivery is April 12, 2027.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to use the calculator<\/h2>\n<ol>\n<li>In <strong>Last menstrual period<\/strong>, select the first day your most recent menstrual period began\u2014not the day bleeding ended or the date you think conception occurred. The field initially shows today\u2019s date, so change it to your actual date.<\/li>\n<li>In <strong>Cycle Length<\/strong>, enter the usual number of days from the first day of one period to the first day of the next. The default is 28 days; the accepted range is 20 to 45 days.<\/li>\n<li>Read <strong>Weeks<\/strong> and <strong>Days<\/strong> together for your estimated gestational age. <strong>Estimated Date of Delivery<\/strong> gives the corresponding due date. The calculation uses today\u2019s date, so the weeks-and-days result changes over time.<\/li>\n<\/ol>\n<h2>What gestational age means<\/h2>\n<p>Gestational age describes how far a pregnancy has progressed. It is conventionally counted from the first day of the last menstrual period, rather than from conception. For example, a result of 12 weeks and 0 days means 12 completed weeks have elapsed according to the calculator\u2019s adjusted starting date; it does not mean conception happened 12 weeks ago.<\/p>\n<p>Clinicians use gestational age to place ultrasound findings, fetal growth, screening tests, and pregnancy milestones in context. A 40-week pregnancy is the basis of this calculator\u2019s estimated delivery date, but that date is a reference point, not a prediction of the exact day of birth. If you want to compare methods of estimating that date, see the <a href=\"https:\/\/wpcalc.com\/en\/pregnancy-baby\/pregnancy-due-date\/\">Pregnancy Due Date calculator<\/a>.<\/p>\n<p>The cycle-length adjustment accounts for a simple timing assumption: compared with a 28-day cycle, ovulation may occur later in a longer cycle or earlier in a shorter one. A 30-day cycle therefore shifts the calculated starting date two days forward and the delivery estimate two days later. It does not measure when ovulation or conception actually occurred.<\/p>\n<h2>Assumptions and limitations<\/h2>\n<ul>\n<li><strong>The period date needs to be reliable.<\/strong> If you are unsure when your last period began, or bleeding was not a typical period, the estimate may be inaccurate.<\/li>\n<li><strong>Cycle length is an approximation.<\/strong> Ovulation does not always occur on the same cycle day, even when periods seem regular. Irregular cycles, recent hormonal contraception, breastfeeding, and other factors can make period-based dating less dependable.<\/li>\n<li><strong>Future dates are not meaningful as a current gestational age.<\/strong> Enter a last menstrual period that has already occurred. Near midnight or a daylight-saving-time change, date handling may also produce a one-day difference from a calendar count.<\/li>\n<li><strong>Clinical dating can differ.<\/strong> A healthcare professional may use an early ultrasound and your medical history to establish or revise the pregnancy\u2019s official dating. The <a href=\"https:\/\/wpcalc.com\/en\/pregnancy-baby\/ultrasound-gestation-period\/\">Ultrasound Gestation Period calculator<\/a> and <a href=\"https:\/\/wpcalc.com\/en\/pregnancy-baby\/crown-rump-length\/\">Crown Rump Length calculator<\/a> can help you understand measurements, but they do not replace a clinical assessment.<\/li>\n<\/ul>\n<p>Use this result as an estimate for planning and discussion, not as confirmation of pregnancy or a substitute for prenatal care. If your calculated dates and an ultrasound report disagree, ask your healthcare professional which dating estimate to follow.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Estimate gestational age in weeks and days and an expected delivery date. Enter the first day of your last menstrual period and your usual cycle length.<\/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":[45],"tags":[47],"class_list":["post-57732","post","type-post","status-publish","format-standard","hentry","category-pregnancy-baby","tag-pregnancy-tracking"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/57732","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=57732"}],"version-history":[{"count":4,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/57732\/revisions"}],"predecessor-version":[{"id":65383,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/57732\/revisions\/65383"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=57732"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=57732"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=57732"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}