Old Calendar vs New Calendar
The Julian and Revised Julian calendars in the Orthodox Church, explained.
Short answer: "Old Calendar" Orthodox churches keep fixed feasts on the Julian calendar, currently 13 days behind the civil calendar. "New Calendar" churches use the Revised Julian calendar, which matches the civil date. Both calculate Pascha the same way, so Easter and the feasts that depend on it fall on the same day.
Side by side
| New Calendar | Old Calendar | |
|---|---|---|
| Calendar | Revised Julian (1923) | Julian |
| Nativity of Christ | December 25 | January 7 (civil) |
| Theophany | January 6 | January 19 (civil) |
| Dormition | August 15 | August 28 (civil) |
| Pascha | Same date — Julian paschalion | |
Which churches use which calendar
New Calendar: the Ecumenical Patriarchate (including the Greek Orthodox Archdiocese of America), the Churches of Greece, Cyprus, Antioch, Alexandria, Romania and Bulgaria, and most parishes of the Orthodox Church in America.
Old Calendar: the Churches of Jerusalem, Russia (including ROCOR), Serbia, Georgia, Mount Athos, and some OCA parishes and dioceses.
Why the calendars differ
The Julian calendar adds a leap day every four years, which makes its year slightly too long. The Gregorian reform of 1582 corrected this, and in 1923 a pan-Orthodox congress in Constantinople adopted the Revised Julian calendar, which matches the Gregorian calendar until 2800. Not every Church accepted the change.
Apostles' Fast length
Because Pascha is shared but June 29 is a fixed feast, the Apostles' Fast is 13 days longer on the Old Calendar. In some New Calendar years — such as 2027 — it lasts only a day or is absent.
Switch between calendars on the Orthodox Calendar Today page.
Frequently asked questions
Why do some Orthodox celebrate Christmas on January 7?
Old Calendar churches keep December 25 on the Julian calendar, which currently falls on January 7 of the civil (Gregorian) calendar.
Do Old and New Calendar Orthodox celebrate Pascha on the same day?
Yes. Almost all Eastern Orthodox churches, on either calendar, calculate Pascha with the Julian paschalion, so Easter falls on the same Sunday. The Church of Finland is the main exception.
How many days apart are the two calendars?
From 1900 to 2099 the Julian calendar runs 13 days behind the Gregorian and Revised Julian calendars. The gap grows to 14 days in 2100.
Which calendar does this site use?
Both. The calendar defaults to the New Calendar, and an Old Calendar toggle shifts fixed feasts and saints by 13 days. Movable feasts are the same on both.
Sources
- Orthodox Church in America — Feasts & Saints
- Greek Orthodox Archdiocese of America — Chapel calendar
- orthocal.info — Julian/Revised Julian calendar data
Local practice varies by jurisdiction and parish. Follow the guidance of your priest or spiritual father.