Concise Lexicon of Christianity

Ken Collins’ Website

Teachings, worship, rites, sermons, and terminology

Find Holy Days

You can use this page to generate a list of the holy days in the year you specify. If you are wondering when Easter Day falls in a given year, this is how to find out.

Before 1875, some local areas might have had their own dates for Easter. Many Protestant churches didn’t adopt the Gregorian calendar until their national government did.

Three calendars are currently in use in Christendom:

Western Holy Days

The Western Church includes the Roman Catholic Church, the Anglican Communion, and all Protestant bodies—often called the western church. You can read information about western holy days.

You can generate a calendar that is valid for the Western Church, which uses the Gregorian Calendar. The first full Gregorian year was 1583. You can generate a calendar for any year from 1583 to 999999.

You can generate a calendar for any year you like, but if your plans require you to know the date of Easter after 9999, I would be very interested in learning the details of your diet, medications, and exercise regimen.

Western Holy Days

Enter a year: then

My method of determining the western date of Easter may produce errors before 1875. Some regions retained their own methods of calculating Easter.

Eastern Holy Days

The Eastern Church includes the Eastern Orthodox churches, the Oriental Orthodox churches, and the eastern-rite churches that are affiliated with the Roman Catholic Church.

You can generate a calendar that is valid for most eastern churches. The current method of calculating Easter was first instituted by the Council of Nicæa in AD 325. You can enter any year after 325.

Eastern Holy Days

Enter a year: then

You can also use this to estimate the date of Easter Day in any year before 1583, or in English-speaking countries before 1753. If you are looking for the dates of holy days in the Finnish Orthodox Church, you are on your own, because it is the only orthodox church that uses the Gregorian calendar.

This program is as accurate as I can make it; however, I offer no warranty for accuracy.

The Three Calendars

The Julian Calendar

The Julian calendar is named after Julius Caesar, who proposed a reform of the Roman civil calendar. It took effect in 45 BC. The month of Quintilis was renamed July in his honor. After Caesar Augustus made some minor but necessary changes, so the month of Sextilis was renamed August in his honor.

The Julian calendar unlinked the months from lunar phases, and inserted a day every fourth year to make the calendar come out even with the seasons. After our current year-numbering system took effect, every year divisible by four was a leap year. The average length of the Julian year is 365.25 days. It gets out of synch with the seasons by one day every 128 years.

The First Ecumenical Council of Nicæa based the formula for calculating the date of Easter on this calendar.

The Gregorian Calendar

Adding a leap year every four years is too often. Over centuries, the days accumulated, and dates were falling later in the seasons. For this reason, Pope Gregory revised the Julian Calendar in 1582, and it is called the Gregorian calendar in his honor.

The first year of the Gregorian calendar omitted ten days from October to get things back in synch, and adjusted the leap-year rule to keep it that way. Applying the Nicæan rule to the Gregorian calendar puts Easter at the right tim of the year.

The Gregorian calendar has a leap day in every year divisible by four, just like the Julian calendar, but only in century years that are divisible by 400. Thus there was a January 29 in 2000, but not in 1900. The average length of the Gregorian year is 365.2425 years. It gets out of synch with the seasons by one day every 7,700 years.

Because the Gregorian calendar was instituted by the Catholic Church, Protestant and Orthodox countries were slow to adopt it as their civil calendar. The changeover lasted from 1582 to 1923. The last country to adopt it was Greece. It is now in almost universal use as a civil calendar.

The Revised Gregorian Calendar

Unlike the Julian and Gregorian calendars, the Revised Julian Calendar has never been used as a civil calendar. It is strictly an ecclesiastical calendar in limited use.

The Revised Gregorian calendar was proposed by Maksim Trpković in 1923 as an improvement over the Gregorian calendar. It is very close to the Gregorian calendar but more accurate. In the Revised Gregorian calendar, every year divisible by four has a leap day, but century years do not have leap days unless the result of dividing the year by 900 results in a remainder of 200 or 600. The average Revised Gregorian year is 48 seconds shorter than 365.2425 days.

Some Orthodox churches, called new calendarists, have adopted the Revised Gregorian calendar. Most Orthodox churches still use the Julian calendar.

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