{"id":67373,"date":"2026-10-21T10:06:40","date_gmt":"2026-10-21T07:06:40","guid":{"rendered":"https:\/\/wpcalc.com\/en\/?p=67373"},"modified":"2026-10-21T10:06:40","modified_gmt":"2026-10-21T07:06:40","slug":"julian-date-converter","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/life\/julian-date-converter\/","title":{"rendered":"Julian Date Converter"},"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\">Convert Between Calendar Dates, Ordinal Dates and Julian Day Numbers<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"67373\" data-favorite-title=\"Julian Date\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/life\/julian-date-converter\/\" data-favorite-excerpt=\"Convert ordinal dates (YYYY-DDD \/ YYDDD) to calendar dates, and calendar dates with a UTC time to astronomical Julian dates (JD) and Modified Julian Dates (MJD) \u2014 or back the other way. Includes a live day-of-year clock and a day-of-year table for the current year.\" 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\/julian-date-converter\/\" method=\"POST\" class=\"calculator\" id=\"calculator-67373\" data-post=\"67373\"><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\">Conversion Mode<\/label><div class=\"grid grid-cols-1\"><select id=\"field-1\" name=\"conversion_mode\"><option value=\"ord_to_cal\" selected>Ordinal date \u2192 calendar date<\/option><option value=\"cal_to_ord\">Calendar date \u2192 ordinal date<\/option><option value=\"to_jd\">Date and UTC time \u2192 JD \/ MJD<\/option><option value=\"from_jd\">JD \u2192 date and UTC time<\/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=\"is-single field\" id=\"input-2\"><span class=\"font-semibold\">Ordinal Date Input<\/span><\/div><div class=\"field has-term\" id=\"input-3\"><label for=\"field-3\">Ordinal Date<\/label><div class=\"term\">DDD<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"text\" name=\"ordinal_date\" id=\"field-3\" aria-describedby=\"calc-info-3\" placeholder=\"2024173, 24173 or 2024-173\" step=\"any\" value=\"2024173\"\/><small id=\"calc-info-3\">YYDDD (5 digits), YYYYDDD (7 digits) or YYYY-DDD. The day number is 001\u2013366; day 366 exists only in leap years. Two-digit years: 00\u201368 mean 20xx, 69\u201399 mean 19xx.<\/small><\/div><div class=\"is-single field\" id=\"input-4\"><span class=\"font-semibold\">Calendar Date Input<\/span><\/div><div class=\"field\" id=\"input-5\"><label for=\"field-5\">Date<\/label><input type=\"date\" name=\"date\" id=\"field-5\" step=\"any\" value=\"2024-06-21\"\/><\/div><div class=\"field\" id=\"input-6\"><label for=\"field-6\">Time (UTC)<\/label><input type=\"time\" name=\"time_utc\" id=\"field-6\" aria-describedby=\"calc-info-6\" step=\"any\" value=\"12:00\"\/><small id=\"calc-info-6\">Universal time. The Julian day starts at noon UTC, so 12:00 UTC gives a whole-number JD.<\/small><\/div><div class=\"field has-term\" id=\"input-7\"><label for=\"field-7\">Julian Date (JD)<\/label><div class=\"term\">JD<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"number\" name=\"julian_date_jd\" id=\"field-7\" aria-describedby=\"calc-info-7\" min=\"-999999999\" max=\"999999999\" step=\"any\" value=\"2460000.5\"\/><small id=\"calc-info-7\">Astronomical Julian date, e.g. 2460000.5. Values before 2299160.5 (before 15 Oct 1582) are interpreted with the historical Julian calendar.<\/small><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"67373\">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> Conversion Results<\/h3><div class=\"result-box\"><div class=\"field-result is-column\" id=\"output-1\"><span class=\"field-title\"><span>Today&#039;s Values<\/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>Calendar Date<\/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>Ordinal Date (YYYY-DDD)<\/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>Ordinal Date (YYDDD)<\/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 class=\"field-result\" id=\"output-5\"><span class=\"field-title\"><span>Day of Year<\/span><\/span><span class=\"field-value\" id=\"result-5\"><\/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-6\"><span class=\"field-title\"><span>Julian Date (JD)<\/span><span class=\"result-term\">JD<\/span><\/span><span class=\"field-value\" id=\"result-6\"><\/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-7\"><span class=\"field-title\"><span>Modified Julian Date (MJD)<\/span><span class=\"result-term\">MJD<\/span><\/span><span class=\"field-value\" id=\"result-7\"><\/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-8\"><span class=\"field-title\"><span>Date and Time (UTC) from JD<\/span><\/span><span class=\"field-value\" id=\"result-8\"><\/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-9\"><span class=\"field-title\"><span>How It Works<\/span><\/span><span class=\"field-value\" id=\"result-9\"><\/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-10\"><span class=\"field-title\"><span>Day-of-Year Table (Current Year)<\/span><\/span><span class=\"field-value\" id=\"result-10\"><\/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=\"67373\" 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>Julian Date 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} y' &amp;= y + 4800 - \\left\\lfloor \\tfrac{14 - m}{12} \\right\\rfloor, \\qquad m' = m + 12\\left\\lfloor \\tfrac{14 - m}{12} \\right\\rfloor - 3 \\\\ \\mathrm{JDN} &amp;= d + \\left\\lfloor \\frac{153m' + 2}{5} \\right\\rfloor + 365\\,y' + \\left\\lfloor \\frac{y'}{4} \\right\\rfloor - \\left\\lfloor \\frac{y'}{100} \\right\\rfloor + \\left\\lfloor \\frac{y'}{400} \\right\\rfloor - 32045 \\\\ \\mathrm{JD} &amp;= \\mathrm{JDN} - 0.5 + \\frac{t}{86400} \\end{aligned} \\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(d, m, y\\) \u2014 day, month and year of a Gregorian calendar date<\/li>\n<li>\\(t\\) \u2014 the time of day expressed in seconds after 00:00 UTC<\/li>\n<li>\\( \\lfloor \\cdot \\rfloor \\) \u2014 the floor function (rounding down to the nearest integer)<\/li>\n<li>JDN \u2014 the Julian day number, an integer that labels one whole calendar day<\/li>\n<\/ul>\n<p>The first two lines are the Fliegel\u2013Van Flandern algorithm: they turn a calendar date into the continuous count of days that started on 1 January 4713 BC. The third line adds the fraction of the day; because the astronomical Julian day begins at 12:00 UTC, a time of noon produces a whole-number JD and midnight produces a JD ending in .5. Ordinal dates use the same day numbering within a single year: the ordinal date YYYY-DDD simply replaces the month and day with the day-of-year number.<\/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>Julian Date \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> the ordinal date 2024-173 (written 2024173 or 24173 in compact form) \u2014 day 173 of 2024, a leap year.<\/p>\n<p>\\[ 31 + 29 + 31 + 30 + 31 = 152, \\qquad 173 - 152 = 21 \\;\\Rightarrow\\; 21\\ \\text{June}\\ 2024 \\]<\/p>\n<p>At 12:00 UTC that same day corresponds to:<\/p>\n<p>\\[ \\mathrm{JD} = 2460483, \\qquad \\mathrm{MJD} = 2460483 - 2400000.5 = 60482.5 \\]<\/p>\n<p><strong>Result:<\/strong> 2024-173 is Friday, 21 June 2024 \u2014 day 173 of 366, with 193 days remaining in the year. At 12:00 UTC it equals JD 2460483 and MJD 60482.5.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to use the calculator<\/h2>\n<ol>\n<li>Open the <strong>Conversion Mode<\/strong> dropdown and pick the direction you need: ordinal date to calendar date, calendar date to ordinal date, date and UTC time to JD\/MJD, or JD back to a date and time. Only the input fields used by the selected mode are shown.<\/li>\n<li>For the ordinal-date modes, type the code into <strong>Ordinal Date<\/strong> or read the result under <strong>Ordinal Date (YYYY-DDD)<\/strong> and <strong>Ordinal Date (YYDDD)<\/strong>. Accepted input formats are YYYYDDD (7 digits), YYDDD (5 digits) and YYYY-DDD.<\/li>\n<li>For the JD modes, set the <strong>Date<\/strong> and <strong>Time (UTC)<\/strong> fields, or enter a number into <strong>Julian Date (JD)<\/strong>. Remember that the Julian day starts at noon UTC, so 12:00 UTC gives a whole-number JD.<\/li>\n<li>Read the results: <strong>Calendar Date<\/strong> with weekday, <strong>Day of Year<\/strong>, <strong>Julian Date (JD)<\/strong>, <strong>Modified Julian Date (MJD)<\/strong> or <strong>Date and Time (UTC) from JD<\/strong>. A live line above the results always shows today's ordinal and Julian dates, and the day-of-year table beneath lists the cumulative day numbers of the current year.<\/li>\n<\/ol>\n<h2>What is a Julian date?<\/h2>\n<p>The term covers two different conventions, and this converter handles both. In manufacturing, logistics and the military, a Julian date (more precisely an <em>ordinal date<\/em>) is the year followed by the day number within that year: 2024-173 means the 173rd day of 2024. ISO 8601 defines this format, and the compact YYDDD form (24173) is widespread on food packaging for lot and sell-by dating, so a quick conversion to a readable calendar date is often needed.<\/p>\n<p>In astronomy and other sciences that handle long time spans, the Julian date (JD) is a continuous count of days and fractions of days since noon UTC on 1 January 4713 BC. Being a single number that never resets, it makes date arithmetic trivial: subtracting two JDs gives the elapsed days directly. The Modified Julian Date (MJD), defined as JD minus 2400000.5, starts at midnight instead of noon and produces shorter, handier numbers \u2014 most modern catalogs and satellite systems use it.<\/p>\n<p>Interpreting a result takes a little care. A whole-number JD refers to 12:00 UTC of that calendar day; a JD ending in .5 refers to midnight at the start of the day. Ordinal dates always follow Gregorian leap-year rules, so the day number of any date after 28 February shifts by one in a leap year \u2014 21 June is day 172 in a common year but day 173 in a leap year.<\/p>\n<h2>Assumptions, limitations and practical tips<\/h2>\n<ul>\n<li><strong>Day 366 only exists in leap years.<\/strong> The day number runs from 001 to 366; in a common year the calculator rejects 366, because the year has only 365 days.<\/li>\n<li><strong>Two-digit years<\/strong> are expanded per ISO 8601: 00 through 68 mean 2000\u20132068, and 69 through 99 mean 1969\u20131999. To avoid ambiguity, use the four-digit form.<\/li>\n<li><strong>The Gregorian reform of 15 October 1582<\/strong> is respected. JD values before 2299160.5 are interpreted with the historical Julian calendar, and weekday calculations switch automatically, so ancient dates come out correct for their era.<\/li>\n<li><strong>UTC only.<\/strong> JD and MJD are defined in Universal Time; the converter does not shift for your local time zone. If your time is local, convert it first (or use our <a href=\"https:\/\/wpcalc.com\/en\/life\/military-time-converter-24-hour-clock\/\">24-hour clock converter<\/a> to at least check the time format).<\/li>\n<li><strong>Time is rounded to the nearest second<\/strong> when decoding a JD, so a JD with more than five decimals may differ from the displayed time by a fraction of a second.<\/li>\n<li>If you need the elapsed time between two dates instead, see the <a href=\"https:\/\/wpcalc.com\/en\/life\/time-duration-calculator\/\">time duration calculator<\/a> or the <a href=\"https:\/\/wpcalc.com\/en\/life\/time-calculator-add-and-subtract-time\/\">add and subtract time calculator<\/a>.<\/li>\n<\/ul>\n<h2>Reference values<\/h2>\n<p>Useful anchor points for checking conversions:<\/p>\n<table>\n<thead>\n<tr>\n<th>Epoch<\/th>\n<th>JD (UTC)<\/th>\n<th>Date and time (UTC)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Julian day number 0<\/td>\n<td>0.0<\/td>\n<td>1 January 4713 BC (Julian calendar), 12:00<\/td>\n<\/tr>\n<tr>\n<td>MJD = 0<\/td>\n<td>2400000.5<\/td>\n<td>17 November 1858, 00:00<\/td>\n<\/tr>\n<tr>\n<td>Gregorian reform<\/td>\n<td>2299160.5<\/td>\n<td>15 October 1582, 00:00<\/td>\n<\/tr>\n<tr>\n<td>Unix epoch<\/td>\n<td>2440587.5<\/td>\n<td>1 January 1970, 00:00<\/td>\n<\/tr>\n<tr>\n<td>J2000.0 (standard astronomical epoch)<\/td>\n<td>2451545.0<\/td>\n<td>1 January 2000, 12:00<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"excerpt":{"rendered":"<p>Convert ordinal dates (YYYY-DDD \/ YYDDD) to calendar dates, and calendar dates with a UTC time to astronomical Julian dates (JD) and Modified Julian Dates (MJD) \u2014 or back the other way. Includes a live day-of-year clock and a day-of-year table for the current year.<\/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":[6],"tags":[20],"class_list":["post-67373","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\/67373","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=67373"}],"version-history":[{"count":1,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/67373\/revisions"}],"predecessor-version":[{"id":67374,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/67373\/revisions\/67374"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=67373"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=67373"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=67373"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}