{"id":67159,"date":"2026-10-20T09:51:52","date_gmt":"2026-10-20T06:51:52","guid":{"rendered":"https:\/\/wpcalc.com\/en\/?p=67159"},"modified":"2026-10-20T09:51:52","modified_gmt":"2026-10-20T06:51:52","slug":"period-calculator-next-period-date","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/pregnancy-baby\/period-calculator-next-period-date\/","title":{"rendered":"Period Calculator \u2013 Next Period Date"},"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\">Predict Your Next Period and Upcoming Cycles<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"67159\" data-favorite-title=\"Period\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/pregnancy-baby\/period-calculator-next-period-date\/\" data-favorite-excerpt=\"Estimate your next period date and upcoming cycles. Enter the first day of your last period, your average cycle length, period length, and how many cycles to show.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-ovum-sperm\">\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\/period-calculator-next-period-date\/\" method=\"POST\" class=\"calculator\" id=\"calculator-67159\" data-post=\"67159\"><fieldset class=\"fieldset-input is-2\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field is-single\" id=\"input-1\"><label for=\"field-1\">First day of last period<\/label><input type=\"date\" name=\"first_day_of_last_period\" id=\"field-1\" aria-describedby=\"calc-info-1\" step=\"any\" value=\"2026-10-05\"\/><small id=\"calc-info-1\">Enter the first day of bleeding, not the day your period ended.<\/small><\/div><div class=\"field\" id=\"input-2\"><label for=\"field-2\">Average cycle length<\/label><input type=\"text\" name=\"average_cycle_length\" id=\"field-2\" aria-describedby=\"calc-unit-2 calc-info-2\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"21\" max=\"45\" value=\"28\"\/><div class=\"unit\" id=\"calc-unit-2\">days<\/div><small id=\"calc-info-2\">Count from the first day of one period to the first day of the next.<\/small><\/div><div class=\"field\" id=\"input-3\"><label for=\"field-3\">Period length<\/label><input type=\"text\" name=\"period_length\" id=\"field-3\" aria-describedby=\"calc-unit-3\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"2\" max=\"10\" value=\"5\"\/><div class=\"unit\" id=\"calc-unit-3\">days<\/div><\/div><div class=\"field\" id=\"input-4\"><label for=\"field-4\">Cycles to show<\/label><input type=\"text\" name=\"cycles_to_show\" id=\"field-4\" aria-describedby=\"calc-unit-4\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" min=\"1\" max=\"12\" value=\"6\"\/><div class=\"unit\" id=\"calc-unit-4\">cycles<\/div><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"67159\">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 Period Predictions<\/h3><div class=\"result-box\"><div class=\"field-result is-column\" id=\"output-1\"><span class=\"field-title\"><span>Next period<\/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>Upcoming cycles<\/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 is-column\" id=\"output-3\"><span class=\"field-title\"><span>Three-month calendar<\/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 is-column\" id=\"output-4\"><span class=\"field-title\"><span>About these predictions<\/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=\"67159\" 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>Period 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}n&amp;=\\max\\!\\left(1,\\left\\lceil\\frac{T-L}{C}\\right\\rceil\\right)\\\\S_i&amp;=L+(n+i)C\\\\E_i&amp;=S_i+P-1\\\\O_i&amp;=S_i-14\\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 period<\/li>\n<li>\\(T\\) \u2014 today's date<\/li>\n<li>\\(C\\) \u2014 average cycle length in days<\/li>\n<li>\\(P\\) \u2014 period length in days<\/li>\n<li>\\(n\\) \u2014 number of cycles advanced to reach the first upcoming predicted start<\/li>\n<li>\\(i\\) \u2014 upcoming cycle index, starting at 0<\/li>\n<li>\\(S_i\\), \\(E_i\\), and \\(O_i\\) \u2014 predicted period start, period end, and estimated ovulation date<\/li>\n<\/ul>\n<p>The calculator adds whole cycle lengths to the last period's start and skips predicted starts before today. It estimates ovulation 14 days before each predicted period and the fertile window from five days before ovulation through one day after.<\/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>Period \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> On October 20, 2026, enter October 5, 2026, as the first day of your last period, a 28-day average cycle, a five-day period, and six cycles to show.<\/p>\n<p>\\[\\begin{aligned}\\text{Next start}&amp;=\\text{October 5, 2026}+28\\text{ days}=\\text{November 2, 2026}\\\\\\text{Period end}&amp;=\\text{November 2}+4\\text{ days}=\\text{November 6, 2026}\\\\\\text{Estimated ovulation}&amp;=\\text{November 2}-14\\text{ days}=\\text{October 19, 2026}\\\\\\text{Fertile window}&amp;=\\text{October 14\u201320, 2026}\\end{aligned}\\]<\/p>\n<p><strong>Result:<\/strong> The next predicted period starts November 2, 2026\u2014in 13 days\u2014and ends November 6. The table shows six upcoming cycles, with the next starts on November 30 and December 28, 2026; and January 25, February 22, and March 22, 2027.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to use the calculator<\/h2>\n<ol>\n<li>Set <strong>First day of last period<\/strong> to the first day bleeding began, not the day it stopped. The date cannot be in the future.<\/li>\n<li>Enter <strong>Average cycle length<\/strong> in days. Count from the first day of one period to the first day of the next, rather than counting only the days without bleeding. The calculator accepts whole numbers from 21 to 45 days.<\/li>\n<li>Enter <strong>Period length<\/strong>: the number of days bleeding usually lasts, from 2 to 10 days.<\/li>\n<li>Choose <strong>Cycles to show<\/strong>, from 1 to 12. This controls how many upcoming cycles appear in the table, not how many months appear in the calendar.<\/li>\n<\/ol>\n<p>Read <strong>Next period<\/strong> for the predicted start date and days until it. <strong>Upcoming cycles<\/strong> lists predicted start and end dates, estimated ovulation, and fertile windows. The <strong>Three-month calendar<\/strong> covers the current month and the next two months; it may show your most recent predicted period for context. Look at the table if a selected cycle falls beyond those three months.<\/p>\n<h2>What a period prediction means<\/h2>\n<p>A menstrual cycle begins on the first day of a period and ends the day before the next one begins. If your cycles tend to last a similar number of days, adding your average cycle length to the last start date gives a useful planning estimate. The calculator repeats that interval for each upcoming cycle. If a calculated start date has already passed, it advances to the next predicted start, so the upcoming-cycles table does not begin with a past date.<\/p>\n<p>Period length determines the predicted bleeding dates. For a five-day period beginning November 2, the displayed dates are November 2 through November 6, inclusive. Period length does not change the cycle interval: your next start is calculated from one start date to another, even if bleeding lasts longer or shorter than expected.<\/p>\n<p>The ovulation and fertile-window dates are rough estimates, not observations of what your body is doing. This calculator places ovulation 14 days before each predicted period and marks a window from five days before that date through one day after it. For a closer look at calendar-based estimates, see the <a href=\"https:\/\/wpcalc.com\/en\/pregnancy-baby\/fertility-ovulation-calendar-2\/\">ovulation and fertility calendar<\/a>. Neither calendar can confirm that ovulation occurred.<\/p>\n<h2>Assumptions and practical limits<\/h2>\n<p>All predictions assume the same cycle length and period length repeat. Real cycles can vary from month to month, so dates farther into the future may be less useful. Stress, illness, travel, medication, breastfeeding, perimenopause, and other changes can affect timing. If your cycles vary, consider averaging several recent start-to-start intervals, and update the first-day date whenever a new period begins.<\/p>\n<p>The estimated fertile window is <strong>not a reliable way to prevent pregnancy<\/strong>. Ovulation can shift, and a calendar prediction cannot identify days when pregnancy is impossible. If your period is late and pregnancy is possible, a <a href=\"https:\/\/wpcalc.com\/en\/pregnancy-baby\/pregnancy-test-date-calculator\/\">pregnancy test date calculator<\/a> can help you plan when to test; follow the test instructions and seek medical advice if you have concerns.<\/p>\n<p>Seek medical advice if you have unusually heavy bleeding, severe pain, missed periods without a clear reason, or a substantial change in your usual pattern. This tool provides dates for planning and tracking, not a diagnosis.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Estimate your next period date and upcoming cycles. Enter the first day of your last period, your average cycle length, period length, and how many cycles to show.<\/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":[45],"tags":[46],"class_list":["post-67159","post","type-post","status-publish","format-standard","hentry","category-pregnancy-baby","tag-fertility-conception"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/67159","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=67159"}],"version-history":[{"count":1,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/67159\/revisions"}],"predecessor-version":[{"id":67214,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/67159\/revisions\/67214"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=67159"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=67159"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=67159"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}