SuperDevTools
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Hijri date converter, Julian day and Hebrew calendar

Date to convert

The same date in every calendar

The starting calendar you pick is remembered on this device. No date is sent anywhere: everything is calculated in your browser.

One date, every calendar at once

This converter shows a single day in a dozen calendars side by side: Gregorian, Julian, the astronomers' Julian day, Hijri (Umm al-Qura and tabular), Hebrew, Persian, Chinese, Japanese, Buddhist and French Republican, plus the ISO week and Unix time. Useful for dating old records or checking an astronomy exercise.

How to use it

  1. Pick the "Starting calendar": Gregorian, Julian, Hijri, Hebrew, Persian, French Republican or "Julian day (JD)".
  2. Enter the day, month and year, and if needed the "Time (UTC)".
  3. Read "The same date in every calendar". "Today" loads the current moment.
  4. "Copy results" copies every line; "Copy link" gives an address that reopens the same date.

When you start from the Hijri, Hebrew or Persian calendar, the tool scans: it steps through nearby days with your browser's built-in calendar until it finds the date you typed. The month list follows the year entered.

Solar, lunar and lunisolar calendars

A solar calendar follows the seasons: Gregorian, Julian and Persian. A lunar calendar follows the phases of the Moon: the Islamic calendar has 12 months of 29 or 30 days, 354 or 355 days in all, so it moves about 11 days earlier each year against the seasons. A lunisolar calendar adds a month from time to time, as the Hebrew and Chinese calendars do.

Julian to Gregorian

The Julian calendar has a leap year every four years, which makes its year 11 minutes too long. The 1582 reform dropped ten days and three leap years every four centuries (1900 was not a leap year, 2000 was). Italy and Spain went from Thursday 4 October 1582 straight to Friday 15 October. Britain and its American colonies waited until 1752, when 2 September was followed by 14 September. Today the gap is 13 days: 14 November 2026 is 1 November 2026 in the Julian calendar, and 4 July 1776 was 23 June 1776 Julian. Enter a date between 5 and 14 October 1582 and the tool warns that it never existed and shows both readings: proleptic Gregorian (the calendar extended backwards) and Julian, with a "Read as a Julian date" button.

The Hijri calendar and the crescent moon

It counts from the Hijra, in 622. In many countries each month begins when the first crescent is sighted, so it can differ by a day from one country to the next. The tool gives two calculations: Umm al-Qura, the official calendar of Saudi Arabia, and the arithmetic tabular calendar. For 14 November 2026 they give Jumada II 4, 1448 and Jumada II 3, 1448. Both are forecasts.

Hebrew and Persian

The Hebrew calendar adds a thirteenth month in seven years out of nineteen, and each day begins at sunset the evening before. Year 5787 began on 12 September 2026, and 14 November 2026 is 4 Kislev 5787. The Persian calendar, official in Iran, starts its year at the March equinox with Nowruz: 1 Farvardin 1405 falls on 21 March 2026.

French Republican calendar

Twelve months of 30 days split into three ten-day weeks, plus 5 or 6 complementary days. Year I began on 22 September 1792; the calendar was adopted in October 1793 and dropped on 1 January 1806. The tool follows the legal rule: each year begins on the day of the autumn equinox in Paris, computed to the minute. It matches the historical years, such as 18 Brumaire year VIII, 9 November 1799. After 1805 some converters use a fixed leap rule that was never applied and can be one day off, mostly when the equinox falls minutes from midnight (1840, 1902, 1997).

Julian day in astronomy

The Julian day (JD) counts days from noon on 1 January 4713 BC. 1 January 2000 at 12:00 UTC is exactly 2451545.0. The Modified Julian Day (MJD) subtracts 2400000.5 and starts at midnight: 14 November 2026 at 00:00 UTC is MJD 61358.

Frequently asked questions

Why is my Hijri date one day off?

The start of each month depends on the crescent sighting where you live; the official announcement can come a day before or after the calculation.

How do I enter a year BC?

Use astronomical numbering: 0 for 1 BC, -1 for 2 BC.

Does the Chinese line show the zodiac sign?

No. It shows the year, its place in the 60-year cycle, the month and the day, with no interpretation.

Are my dates sent anywhere?

No. Everything runs on your device; only the starting calendar is remembered.