About Date Converters

Date Converters converts a date between the forms people meet at work and in daily life: the codes on packaging and in logistics systems, the timestamps in software and spreadsheets, the formats used in different countries, and the calendars that set religious and national holidays. Every converter works in both directions and explains how its system works, so you can check a result instead of taking it on trust.

What the converters cover

• Julian date: Today's Julian date in YYDDD, YYYYDDD and YDDD form, with a two-way converter, a batch box for lists of codes and the rules for reading 3- to 7-digit Julian dates.
• Day of year: What day of the year is it? Today's day number out of 365 or 366, days left, share of the year passed, the ISO ordinal date and a day number to date converter.
• Week number: What week is it? Today's ISO 8601 week number with its Monday to Sunday dates, the US week number shown separately, and a converter between dates and weeks.
• ISO 8601: ISO 8601 format explained, with a converter that parses any ISO 8601 string and writes calendar, week and ordinal dates, UTC with Z, offsets and Unix seconds.
• Military date: Military date format for today and any date: DDMMMYY (23OCT26), DD MMM YYYY, a date-time group builder with zone letters, YDDD Julian codes and 24-hour time.
• Date formats: Convert a date between MM/DD/YYYY, DD/MM/YYYY, YYYY-MM-DD and written forms, and see which order the US, Europe and Asia use and why 03/04/2026 is ambiguous.
• Unix timestamp: Unix timestamp converter with the current Unix time, seconds, milliseconds or microseconds to UTC and local time, plus code for JavaScript, Python, SQL, Excel.
• Excel date: Excel serial date converter for 1900 and 1904 systems: turn a serial number with decimal time into a date and back, with formulas and the 1900 leap-year bug.
• Julian Day: Julian Day Number calculator for astronomy: convert a UTC date and time to the decimal Julian Date and back, with Modified Julian Date, weekday and Unix time.
• Hijri date: Today's Hijri date in the Umm al-Qura calendar, a Hijri to Gregorian converter with a tabular option and sighting adjustment, and key 1447-1448 AH dates.
• Hebrew date: Hebrew date converter for any Gregorian or Jewish date, with an after-sunset option, year length and leap-year status, and the rules behind Adar I and Adar II.
• Chinese calendar: Chinese lunar calendar converter for 1901-2100: lunar dates in Chinese characters, leap months, the sexagenary year, zodiac animal and New Year dates.
• Persian date: Persian date converter for Shamsi (Solar Hijri) and Gregorian dates, with Iranian and Afghan month names, weekday and Nowruz, and the leap-year rule explained.
• Nepali date: Nepali date converter for Bikram Sambat (BS) and AD dates, 1970-2090 BS, with results in English and Devanagari, the weekday and the 2083 BS month lengths.
• Julian to Gregorian: Julian to Gregorian calendar converter for historical and Orthodox dates: convert either way, with the weekday, day difference and adoption dates by country.

How they work

The calculations run in your browser; nothing you type is sent to us. Pages open with today's date in your time zone and update as you type. Addresses keep the date you entered, so a result can be bookmarked or shared. The site carries no advertising.

Where a calendar follows a rule, we compute it; where it depends on an authority's decisions, as the Saudi Umm al-Qura, Chinese and Nepali calendars do, we use month tables checked against that authority. The method page lists the rules, the tables, their ranges and the test dates every build is checked against.

What they are not

Religious observances follow local announcements, which can differ from any calculated calendar by a day or two. Use the converters to plan, and the announcement of your community or authority to observe.

Corrections

If a result disagrees with an official source, tell us the page, what you entered and the source you are comparing against. We check every report and correct confirmed errors.

The company that publishes Date Converters is identified in our privacy policy. You can reach us at [email protected].