How is the Coptic calendar structured?

The Coptic year has 12 months of 30 days plus a short 13th month called Nasie of 5 days (6 in a leap year, when the year mod 4 equals 3). Years are counted as Anno Martyrum (A.M.), the Year of the Martyrs, beginning in AD 284.

Is my date sent anywhere?

No. The converter is privacy-first — all processing happens locally in your browser and no date ever leaves your device.

Coptic Calendar Converter (A.M. ⇄ Gregorian)

Q: How accurate is the conversion?

It is exact. The converter routes both directions through the Julian Day Number using the standard Coptic epoch (JDN 1825030 = 1 Tout 1 A.M.), so every date maps deterministically with no drift.

Coptic calendar converter

Convert between Gregorian dates and the Coptic calendar (Anno Martyrum / A.M.). The Coptic year has 12 months of 30 days plus a short 13th month, Nasie, of 5 days (6 in a leap year). The converter routes both directions through the Julian Day Number using the standard Coptic epoch (JDN 1825030 = 1 Tout 1 A.M.), so every conversion is exact and deterministic.

It is privacy-first: every calculation happens locally in your browser and nothing is ever sent anywhere.