Julian to Gregorian calendar date converter
Enter the Julian year, month and day to get the Gregorian date, handy for reading old European and Russian records.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter julian year, month and day.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
JDN = day + floor((153m + 2) / 5) + 365y + floor(y / 4) minus 32083, where a = floor((14 minus month) / 12), y = year + 4800 minus a, m = month + 12a minus 3. The number is then turned into a Gregorian date.
Example
Inputs: Julian year = 2,026, Month = 12. December, Day = 25. Result: Gregorian date: Thursday, January 7, 2027 (2027-01-07); Weekday: Thursday; Written out: 7 January 2027.
Limits and caveats
- Accepts years 1000 to 3000.
- Some old records start the year on 25 March rather than 1 January, so adjust the year before entering it if needed.
Questions about this tool
Why is 29 February 1900 accepted?
Every year divisible by 4 is a leap year in the Julian calendar, so 29 February 1900 exists and equals 13 March 1900 Gregorian.
When did Britain switch to the Gregorian calendar?
In September 1752: Thursday 14 September came directly after Wednesday 2 September.
What is the Julian Day Number?
A continuous day count used by astronomers; it is 2299161 on 15 October 1582 Gregorian.