Coptic to Gregorian date converter
Handy for placing a church occasion or a farming season written in Coptic months on the Gregorian calendar.
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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 coptic 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
Julian Day Number = 1825029 + 365 × (year minus 1) + floor(year / 4) + 30 × (month minus 1) + day, then the number is turned into a Gregorian date with the standard algorithm.
Example
Inputs: Coptic year = 1,743, Month = 1. Thout, Day = 1. Result: Gregorian date: Friday, September 11, 2026 (2026-09-11); Weekday: Friday; Written out: 11 September 2026.
Limits and caveats
- Accepts Coptic years 1616 to 1817 (about 1900 to 2100).
- Day 6 of Nasie exists only in years where year mod 4 = 3.
Questions about this tool
What is the gap between Coptic and Gregorian years?
After Nayrouz in September it is the Gregorian year minus 283, and before it minus 284.
Why was day 6 of Nasie rejected?
The chosen year is not a leap year, so its Nasie has only 5 days.
Do Coptic months have fixed lengths?
Yes. All twelve months have 30 days; only Nasie changes between 5 and 6 days.