{"id":57963,"date":"2016-02-06T04:47:46","date_gmt":"2016-02-06T02:47:46","guid":{"rendered":"http:\/\/wpcalc.com\/?p=57963"},"modified":"2026-09-28T10:39:12","modified_gmt":"2026-09-28T07:39:12","slug":"the-day-of-a-year-date-validity","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/life\/the-day-of-a-year-date-validity\/","title":{"rendered":"Day of the Week 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\">Check Day of the Week<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"57963\" data-favorite-title=\"Day of the Week\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/life\/the-day-of-a-year-date-validity\/\" data-favorite-excerpt=\"Enter a day, month, and year to find the day of the week for that date. The calculator also checks whether the date is valid.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-date\">\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\/the-day-of-a-year-date-validity\/\" method=\"POST\" class=\"calculator\" id=\"calculator-57963\" data-post=\"57963\"><fieldset class=\"fieldset-input is-3\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field\" id=\"input-1\"><label for=\"field-1\">Day<\/label><input type=\"text\" name=\"day\" id=\"field-1\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"1\" min=\"1\" max=\"31\" value=\"10\"\/><\/div><div class=\"field\" id=\"input-2\"><label for=\"field-2\">Month<\/label><input type=\"text\" name=\"month\" id=\"field-2\" data-number inputmode=\"decimal\" autocomplete=\"off\" spellcheck=\"false\" placeholder=\"1\" min=\"1\" max=\"12\" value=\"4\"\/><\/div><div class=\"field\" id=\"input-3\"><label for=\"field-3\">Year<\/label><input type=\"number\" name=\"year\" id=\"field-3\" placeholder=\"2026\" step=\"any\" value=\"2025\"\/><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"57963\">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>Day of the Week<\/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><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=\"57963\" 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\">2<\/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\">1<\/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>Day of the Week 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=\\left(q+\\left\\lfloor\\frac{13(m+1)}{5}\\right\\rfloor+K+\\left\\lfloor\\frac{K}{4}\\right\\rfloor+\\left\\lfloor\\frac{J}{4}\\right\\rfloor+5J\\right)\\bmod 7\\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(h\\) \u2014 weekday number: 0 = Saturday, 1 = Sunday, through 6 = Friday<\/li>\n<li>\\(q\\) \u2014 day of the month<\/li>\n<li>\\(m\\) \u2014 adjusted month: March = 3, through December = 12; January = 13 and February = 14 of the previous year<\/li>\n<li>\\(K\\) \u2014 the last two digits of the adjusted year<\/li>\n<li>\\(J\\) \u2014 the century of the adjusted year, rounded down<\/li>\n<\/ul>\n<p>This is Zeller\u2019s congruence for the Gregorian calendar. It explains the weekday mathematically; the calculator itself uses JavaScript\u2019s Date object to validate the date and obtain its weekday.<\/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>Day of the Week \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> find the weekday for April 10, 2025, the calculator\u2019s default date. April is month 4, so \\(q=10\\), \\(m=4\\), \\(K=25\\), and \\(J=20\\).<\/p>\n<p>\\[h=\\left(10+\\left\\lfloor\\frac{13(4+1)}{5}\\right\\rfloor+25+\\left\\lfloor\\frac{25}{4}\\right\\rfloor+\\left\\lfloor\\frac{20}{4}\\right\\rfloor+5(20)\\right)\\bmod 7\\]<\/p>\n<p>\\[h=(10+13+25+6+5+100)\\bmod 7=159\\bmod 7=5\\]<\/p>\n<p><strong>Result:<\/strong> 5 corresponds to Thursday, so April 10, 2025, was a Thursday.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to use the calculator<\/h2>\n<ol>\n<li>Enter the calendar day in <strong>Day<\/strong>, from 1 to 31.<\/li>\n<li>Enter the month number in <strong>Month<\/strong>, from 1 for January to 12 for December.<\/li>\n<li>Enter the four-digit year in <strong>Year<\/strong>. For example, enter 2025 rather than 25.<\/li>\n<li>Read the weekday under <strong>Day of the Week<\/strong>. If the entered date does not exist, the result displays \u201cInvalid Date.\u201d<\/li>\n<\/ol>\n<p>The starting values are Day 10, Month 4, and Year 2025. Leave them unchanged to check the example above, or replace all three values with your own date.<\/p>\n<h2>What the day of the week tells you<\/h2>\n<p>A date identifies a particular day in a calendar year; its weekday identifies its position in the repeating seven-day cycle. Knowing the weekday can help you check an appointment, look up the day on which an event occurred, or plan around workdays and weekends. The same day and month can fall on different weekdays in different years.<\/p>\n<p>The weekday shifts because an ordinary year has 365 days, or 52 full weeks plus one day. A leap year has 366 days, or 52 weeks plus two days. For instance, a date after February may move two weekdays forward from one year to the next when February 29 falls between the dates.<\/p>\n<p>The formula above is one way to calculate a Gregorian weekday by hand. January and February are treated as the final two months of the preceding year, which keeps the formula consistent around leap years. Its result is a number from 0 to 6, so the number must be converted to a weekday name. The calculator performs the date check and returns the name directly; it does not evaluate Zeller\u2019s formula.<\/p>\n<p>If you need to see a date in the context of its full month, use the <a href=\"https:\/\/wpcalc.com\/en\/life\/monthly-calendar\/\">Monthly Calendar Generator<\/a>. To count the elapsed time between two dates rather than identify one weekday, use the <a href=\"https:\/\/wpcalc.com\/en\/life\/days-between-dates\/\">Days Between Dates calculator<\/a>.<\/p>\n<h2>Date validity and practical limitations<\/h2>\n<p>The calculator checks the complete date, not just whether each entry is within its field\u2019s range. April has only 30 days, so April 31 is invalid even though 31 is allowed in the Day field. February 29 is valid only in a leap year. In the Gregorian calendar, a year divisible by 4 is usually a leap year, except century years must also be divisible by 400. Thus, February 29, 2000, is valid, but February 29, 1900, is not. For a quick check of a month\u2019s length, see the <a href=\"https:\/\/wpcalc.com\/en\/life\/days-in-month\/\">Days in Month calculator<\/a>.<\/p>\n<p>The calculator relies on JavaScript\u2019s Date object, which treats dates using the Gregorian calendar rather than switching to the Julian calendar for older historical dates. A date recorded under the Julian calendar may therefore require conversion before its historical weekday can be checked this way. Local time-zone rules can also affect unusual dates that were skipped when a region changed its civil time zone.<\/p>\n<p>Use a full year rather than a one- or two-digit year. JavaScript interprets numeric years from 0 through 99 as 1900 through 1999 when creating a date; this calculator\u2019s validity check will consequently reject those entries. The displayed weekday name follows your browser\u2019s locale, so it may appear in a language other than English.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Enter a day, month, and year to find the day of the week for that date. The calculator also checks whether the date is valid.<\/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":[6],"tags":[20],"class_list":["post-57963","post","type-post","status-publish","format-standard","hentry","category-life","tag-date"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/57963","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=57963"}],"version-history":[{"count":3,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/57963\/revisions"}],"predecessor-version":[{"id":65355,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/57963\/revisions\/65355"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=57963"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=57963"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=57963"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}