Coptic Date Converter
Convert Gregorian and Coptic civil dates in either direction, including the short thirteenth month and leap-day validation.
Starts with an editable example. Replace the dates and rules with your own.
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Choose your dates.
Select your counting rules and calculate.
Calculation details
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How to use this calculator
Enter a Gregorian date or numeric Coptic year, month and day. Converted Gregorian dates must fall in 1900-2100.
Conversion uses the browser's ICU Coptic calendar. Twelve thirty-day months are followed by a five- or six-day thirteenth month. Month names are shown alongside numbers.
A worked example
Gregorian September 11, 2026 corresponds to Coptic 1743-01-01, the first day of Tout.
Does this determine religious day boundaries or feast rules?
No. It converts civil date labels. Religious observance and clock-based day boundaries require separate conventions.
Which calendar and years are supported?
Each result states its calendar, time scale, precision and supported range. Batch converters accept up to 100 nonempty input lines and retain invalid rows. Copy, CSV and print include the calculation rules. Calendar downloads appear when a result contains dated events. Calculations run in your browser; no reminders or jobs are scheduled.
What happens to my dates?
Calculations run on your device. Saving a calculation is optional and keeps it in this browser. A setup link contains the dates and settings you entered; anyone with the link can read them. Use one tab per saved calculator. Clear saved data from Privacy & settings.