About

Great Lent is the most rigorous fasting period in the Eastern Orthodox Church, serving as a spiritual preparation for Pascha (Easter). Unlike fixed-date holidays, the Lenten period shifts every year based on the computation of Pascha, which relies on the Julian calendar and the vernal equinox.

Navigating the dietary rules can be complex. The fast involves not just the abstention from meat and dairy, but specific regulations regarding oil, wine, and fish on particular days. This tool calculates the exact start date (Clean Monday) and breaks down the seven weeks of Lent, highlighting special feast days like the Annunciation and Palm Sunday where strictness is alleviated.

Formulas

The date of Orthodox Pascha is calculated using the Gaussian algorithm for the Julian Calendar, then converted to the Gregorian date. Great Lent begins on Clean Monday, calculated as:

Date_CleanMonday = Date_Pascha − 48 days

Logic for daily rules:

Weekends: Oil ∪ Wine
Annunciation (Mar 25): Fish Allowed
Palm Sunday: Fish Allowed

Reference Data

Week Name	Focus	Typical Dietary Rule
Clean Week (1st)	Purification & Strictness	Strict Fast (No oil/wine). First 3 days often total abstinence.
Weeks 2-5	Spiritual Struggle	Mon-Fri: Strict Fast. Sat-Sun: Wine & Oil allowed.
Cross-Veneration (4th)	Encouragement	Standard Lenten Fast.
Palm Sunday (6th)	Entry into Jerusalem	Fish, Wine, and Oil allowed.
Holy Week (7th)	The Passion of Christ	Strict Fast. Holy Friday: Total abstinence.
Pascha	Resurrection	Fast Broken. All foods allowed.

Frequently Asked Questions

The Orthodox Church calculates Easter based on the older Julian Calendar and strictly adheres to the rule that Easter must occur after the Jewish Passover. The Western Church uses the Gregorian Calendar and different lunar tables, leading to a gap that can range from 0 to 5 weeks.

A strict fast typically implies the abstention from meat, dairy, eggs, fish (with backbones), olive oil, and wine. In monastic practice, it also implies eating fewer meals per day (often one).

Yes. In the Orthodox tradition, shellfish (shrimp, calamari, crab) are generally considered 'non-blood' foods and are permitted on days when regular fish is prohibited, though moderation is encouraged.

Clean Monday (Kathara Deftera) marks the very first day of Great Lent. It is a day of strict fasting and spiritual housecleaning, signifying the end of the carnival season (Cheesefare).