About Siyam
Siyam (صيام) is the Arabic word for fasting. In the Coptic Orthodox Christian tradition, fasting involves abstaining from all animal products — meat, poultry, fish, dairy, and eggs — and is typically observed from midnight until mid-afternoon (around 3:00 PM) each fasting day.
This site helps you quickly determine whether a given date falls within one of the Coptic Orthodox fasting periods. Dates are calculated dynamically from the Coptic calendar, so the tool works for any year — not just a single hardcoded season.
The Major Fasting Seasons
| Fast | Duration | When |
|---|---|---|
| Jonah's Fast (Fast of Nineveh) | 3 days | 14 days before Great Lent (always Mon–Wed) |
| Great Lent | 55 days | 55 days before Coptic Easter Sunday |
| Apostles' Fast | Variable | Monday after Pentecost through July 11 |
| Fast of the Virgin Mary | 15 days | August 7–21 (fixed) |
| Nativity Fast | 43 days | November 25 – January 6 (fixed) |
Weekly Fasts
In addition to the major seasons, Coptic Christians fast every Wednesday (commemorating the betrayal of Christ) and every Friday (commemorating the Crucifixion) throughout the year. This weekly fast is suspended during the 50 days of the Pentecost season — from Easter Sunday through Pentecost Sunday.
How the Dates Are Calculated
Coptic Easter is calculated using the ancient Alexandrian computus, which follows the Julian calendar. The Julian Easter date is then converted to the Gregorian calendar by adding 13 days (the Julian–Gregorian offset for the 20th and 21st centuries). All variable fasts — Great Lent, Jonah's Fast, and the Apostles' Fast — are derived from this Easter date.