Easter Calculator - Western and Orthodox Easter Dates

An Easter calculator is a date arithmetic tool that uses the computus, the algorithm the Western Christian churches adopted at the Council of Nicaea in 325 AD, to find the Easter Sunday date for any entered year and returns the date, the weekday label, the offset in days from March 21, and the distance in days from today. The reader enters a year and picks Western (Gregorian) or Orthodox (Julian-based), and the calculator returns the Easter Sunday that the rules of the chosen convention produce for that year.

• • Planning a holiday or school break: A reader who wants to know when Easter Sunday falls in 2026, 2027, or any year they are planning a vacation around enters the year and reads the resulting Sunday date plus the days-until-Easter counter.
• • Reconciling Western and Orthodox dates: A reader who celebrates both Western and Orthodox Easter can switch the method toggle to compare the two dates in the same year without retyping the year.
• • Looking up a historical Easter date: A reader researching a family record or historical event can enter any year from 1583 forward and read the exact Easter Sunday that fell in that year.

Once you know the Easter date, the Calendar Calculator adds or subtracts days from it so you can line up Ash Wednesday, Holy Week, and Pentecost on the same screen.

The calculator takes the entered year and runs the Anonymous Gregorian algorithm for Western Easter or the Meeus Julian algorithm for Orthodox Easter, then builds a UTC Date object from the resulting month and day, reads the weekday label, the offset in days from March 21, and the offset in days from today.

• year: Entered calendar year the algorithm runs on. The Anonymous Gregorian form takes the year mod 19, the century, and the metonic cycle.
• h: Ecclesiastical full moon offset. Encoded from 19a + b - d - g + 15 mod 30, where a is year mod 19 and b, d, g encode the century correction.
• L: Weekday correction. Computed as (32 + 2e + 2i - h - k) mod 7, where e and k are the remainders of b and c divided by 4.
• m: Century correction. Computed as (a + 11h + 22L) div 451, which pulls the result away from April at the end of long cycles.
• • method: Which computus the calculator runs. Western uses the Anonymous Gregorian form; Orthodox uses the Meeus Julian form and adds the century-correct Julian-to-Gregorian offset to convert the Julian result to a Gregorian date.

The day-of-week label is read off the resulting UTC date with the standard Monday through Sunday labels, so a year that lands on March 31 reads Sunday and a year that lands on April 25 also reads Sunday. The offset from March 21 is the integer day count between the Easter date and the ecclesiastical vernal equinox, which is the fixed reference the computus uses. The offset from today is the signed day count between the Easter date and the current UTC date.

According to the USNO Astronomical Applications Department, Easter is the first Sunday following the first ecclesiastical full moon on or after March 21, and Easter can never occur before March 22 or later than April 25; the same article publishes the Anonymous Gregorian algorithm the calculator runs.

If you want to count backward from Easter Sunday to find Ash Wednesday or forward to find Pentecost, the Date Calculator adds or subtracts a fixed number of days from the result without re-entering the year.

Four short definitions keep the Easter arithmetic honest. None of them require the user to derive the algorithm by hand.

Readers who want to see how Western and Orthodox Easter land on different Sundays in the same year can pair the Days Between Dates Calculator with the two results from this calculator to read the gap as a plain day count.

Pick a year, choose a method, and read the Easter date in the result panel. The defaults give you the Western Easter for the current year, so the page shows a real example the first time it loads.

1. 1 Enter the year: Type the four-digit calendar year you want to look up. The field is preloaded with the current year so the result panel shows the upcoming Easter date on first load.
2. 2 Choose Western or Orthodox: Use the Method selector to pick Western (Gregorian) for Catholic and Protestant churches, or Orthodox (Julian-based) for Eastern Orthodox churches. The toggle switches the computus without changing the year.
3. 3 Read the Easter date: The primary result row returns the Easter Sunday date in YYYY-MM-DD form and the weekday label. Western Easter can fall anywhere from March 22 to April 25; Orthodox Easter from April 4 to May 8.
4. 4 Check the equinox offset and days away: The secondary rows return the offset in days between the Easter date and March 21, and the signed distance in days from today.

A reader who wants to know when Easter falls in 2027 enters year 2027, leaves the method set to Western, and reads the result row. The result panel returns 2027-03-28 (Sunday), 7 days after the March 21 equinox.

Once the Easter date is on the screen, the Date Countdown Calculator returns the days, hours, minutes, and seconds to that Sunday.

A short list of what the tool does well, and what it intentionally leaves to other calculators, helps you put the result in the right place in your planning.

• • Two methods in one panel: Western and Orthodox Easter share the same input year and the same result row layout, so the reader can flip between the two conventions in one click.
• • Full computus range: The Anonymous Gregorian algorithm runs from 1583 to 4100, and the Orthodox method applies the century-correct Julian-to-Gregorian offset across the range, so the calculator covers every Easter date a modern reader needs.
• • Weekday, equinox offset, and days-away in one row: The result panel returns the Easter Sunday date, the weekday label, the days from March 21, and the days from today, so the date question and the planning question get answered at the same time.
• • No astronomical moon table required: The computus uses the 19-year Metonic cycle rather than a real lunar table, so the same input gives the same Easter date on every device without depending on ephemeris data.

Once the Easter Sunday is on the screen, the Add Days Calculator offsets the date by a fixed number of days to mark Maundy Thursday (-3), Good Friday (-2), Holy Saturday (-1), Ascension (+39), and Pentecost (+50).

A few inputs change the date, a few change only the offset label, and a few the calculator cannot see at all. Knowing which is which keeps the result honest.

• • The calculator uses the ecclesiastical Paschal full moon, not the astronomical full moon. The two can differ by a day or two in some centuries, so the Easter Sunday the calculator returns is the Sunday the Christian churches would observe rather than the Sunday of the closest astronomical full moon.
• • The Orthodox result is computed under the assumption that the reader wants the Gregorian calendar date, not the Julian calendar date, so the calculator already applies the standard Julian-to-Gregorian offset for the year; readers who need the raw Julian date should subtract the same offset from the result row.

According to the Catholic Encyclopedia, Easter Controversy, the Council of Nicaea in 325 AD set the rule that Easter is the first Sunday after the first ecclesiastical full moon on or after the vernal equinox, the same rule encoded in the Anonymous Gregorian algorithm; the article also states the earliest Easter is March 22 and the latest is April 25, the same 35-day window the calculator outputs.

Readers who want to plan around a wedding anchored to the Easter Sunday of a given year can pair the Wedding Countdown Calculator with the Easter date from this calculator to count down the days, hours, minutes, and seconds.