Computing the church year: Easter, Advent and the propers
Western Easter is the first Sunday after the ecclesiastical full moon that falls on or after 21 March, read from fixed tables rather than the sky, so it always lands between 22 March and 25 April. Ash Wednesday is 46 days before it, Ascension Day 39 days after, Pentecost 49 and Trinity Sunday 56; Advent begins on the Sunday nearest 30 November. The planning desk works all of this out for any year.
Easter
The rules are old and deliberate: the spring equinox is fixed on 21 March, the full moon is the fourteenth day of a tabular lunar month, and Easter is the Sunday after that full moon. Because the moon here is a table, Easter can differ from what an astronomer would predict, and it did in 1962 and 1954 as the US Naval Observatory explains.
The integer algorithm the planner uses was published in 1876 and appears in Meeus's Astronomical Algorithms and Butcher's Ecclesiastical Calendar. The planner's version is tested against the Naval Observatory's published dates of Ash Wednesday, Palm Sunday, Good Friday, Easter, Ascension, Pentecost, Trinity and Advent Sunday for every year from 1990 to 2070.
Everything else
- Advent Sunday: the Sunday between 27 November and 3 December. The church year and the lectionary year (A, B or C) turn over on it; the year ending in 2026 is Year A.
- The Epiphany: 6 January, or the Sunday between 2 and 8 January where it is moved.
- The Baptism of the Lord: the Sunday after the Epiphany (in US Roman Catholic dioceses, the Monday after when the Epiphany is kept on 7 or 8 January).
- The Last Sunday after the Epiphany: the Sunday before Ash Wednesday.
- Propers after Trinity Sunday: in the prayer book, Proper n is the Sunday closest to 11 May plus seven days for each number, so Proper 29 is the Sunday closest to 23 November, the last Sunday before Advent.
- Roman Ordinary Time: counted forward from the Baptism of the Lord, and backward from Christ the King, the 34th Sunday.
Only a few fixed feasts displace a Sunday. In the 1979 prayer book, besides the principal feasts, only the Holy Name, the Presentation and the Transfiguration take precedence of a Sunday, and All Saints' Day may also be kept on the following Sunday.
Worked example: Easter 2027, step by step
| Step | Value | What it is |
|---|---|---|
| a | 13 | year mod 19: the place in the 19 year lunar cycle |
| b | 20 | the century (year divided by 100) |
| c | 27 | the year within the century |
| d | 5 | b divided by 4 |
| e | 0 | b mod 4 |
| f | 1 | (b + 8) divided by 25 |
| g | 6 | (b - f + 1) divided by 3: the lunar correction |
| h | 1 | (19a + b - d - g + 15) mod 30: days from 21 March to the paschal full moon, roughly |
| i | 6 | c divided by 4 |
| k | 3 | c mod 4 |
| l | 5 | (32 + 2e + 2i - h - k) mod 7: days from the full moon to the Sunday |
| m | 0 | (a + 11h + 22l) divided by 451: the correction for two rare cases |
| month | 3 | (h + l - 7m + 114) divided by 31 |
| day | 28 | ((h + l - 7m + 114) mod 31) + 1 |
So Easter 2027 falls on 28 March 2027. The movable feasts for the next ten years, as the planner computes them:
| Year | Ash Wednesday | Easter | Ascension | Pentecost | Advent Sunday |
|---|---|---|---|---|---|
| 2026 | 18 Feb 2026 | 5 Apr 2026 | 14 May 2026 | 24 May 2026 | 29 Nov 2026 |
| 2027 | 10 Feb 2027 | 28 Mar 2027 | 6 May 2027 | 16 May 2027 | 28 Nov 2027 |
| 2028 | 1 Mar 2028 | 16 Apr 2028 | 25 May 2028 | 4 Jun 2028 | 3 Dec 2028 |
| 2029 | 14 Feb 2029 | 1 Apr 2029 | 10 May 2029 | 20 May 2029 | 2 Dec 2029 |
| 2030 | 6 Mar 2030 | 21 Apr 2030 | 30 May 2030 | 9 Jun 2030 | 1 Dec 2030 |
| 2031 | 26 Feb 2031 | 13 Apr 2031 | 22 May 2031 | 1 Jun 2031 | 30 Nov 2031 |
| 2032 | 11 Feb 2032 | 28 Mar 2032 | 6 May 2032 | 16 May 2032 | 28 Nov 2032 |
| 2033 | 2 Mar 2033 | 17 Apr 2033 | 26 May 2033 | 5 Jun 2033 | 27 Nov 2033 |
| 2034 | 22 Feb 2034 | 9 Apr 2034 | 18 May 2034 | 28 May 2034 | 3 Dec 2034 |
| 2035 | 7 Feb 2035 | 25 Mar 2035 | 3 May 2035 | 13 May 2035 | 2 Dec 2035 |
In 2026-27 the first Sunday after Trinity is Proper 4, the Sunday closest to 1 June. The same Sundays named three ways:
| Date | Prayer book propers | Counted after Pentecost | Roman Ordinary Time |
|---|---|---|---|
| 24 Jan 2027 | Third Sunday after the Epiphany | Third Sunday after the Epiphany | Third Sunday in Ordinary Time |
| 13 Jun 2027 | Proper 6 | Fourth Sunday after Pentecost | Eleventh Sunday in Ordinary Time |
| 3 Oct 2027 | Proper 22 | Twentieth Sunday after Pentecost | Twenty-seventh Sunday in Ordinary Time |
| 21 Nov 2027 | Christ the King | Last Sunday after Pentecost: Christ the King | Our Lord Jesus Christ, King of the Universe |
| Date | Day | Season | Colour |
|---|---|---|---|
| 25 Dec 2026 | Christmas Day | Christmas | White |
| 6 Jan 2027 | The Epiphany | Season after the Epiphany | White |
| 10 Jan 2027 | First Sunday after the Epiphany | Season after the Epiphany | White |
| 7 Feb 2027 | Last Sunday after the Epiphany | Season after the Epiphany | White |
| 10 Feb 2027 | Ash Wednesday | Lent | Purple |
| 21 Mar 2027 | Palm Sunday | Holy Week | Red (or purple) |
| 28 Mar 2027 | Easter Day | Easter | White |
| 6 May 2027 | Ascension Day | Easter | White |
| 16 May 2027 | The Day of Pentecost | Easter | Red |
| 23 May 2027 | Trinity Sunday | Season after Pentecost | White |
| 30 May 2027 | Proper 4 | Season after Pentecost | Green |
| 1 Nov 2027 | All Saints' Day | Season after Pentecost | White |
| 21 Nov 2027 | Christ the King | Season after Pentecost | White |
Common mistakes
- Using the astronomical full moon: the church uses tables, so an astronomy website can give the wrong Easter.
- Counting Ash Wednesday as 40 days before Easter: it is 46, because Sundays are not counted in Lent's forty.
- Naming Propers by counting Sundays after Pentecost: the proper depends on the calendar date, not the count.
- Assuming the Epiphany and the Ascension are on the same day everywhere: many dioceses move them to Sundays.
- Reading the lectionary year from the calendar year: it turns over at Advent, not on 1 January.
Plan it now
Open the planning desk to pick this Sunday's hymns with last-sung dates beside them, or the library to enter your hymnal. Everything stays in this browser; nothing is uploaded and there is no account.
Frequently asked questions
What are the earliest and latest dates of Easter?
22 March and 25 April in the Gregorian calendar used by the Western churches.
Why is Easter on a different date in the Orthodox churches?
Most Orthodox churches compute Easter with the older Julian calendar tables, so their Easter usually falls later. The planner computes the Western date.
Which lectionary year are we in?
The three year cycle turns over on Advent Sunday. The church year that ends in a year which leaves a remainder of 1 when divided by 3 is Year A, 2 is Year B, and 0 is Year C, so the year ending in 2026 is Year A and the one ending in 2027 is Year B.
Does the planner include the readings for each Sunday?
No. It works out the Sunday, its proper and its lectionary year; the readings themselves come from your parish, typed or imported.
Sources
Last reviewed 27 September 2026 against:
- The Date of Easter, US Naval Observatory, Astronomical Applications Department, read 27 September 2026. Used for: The ecclesiastical rules for Easter (equinox fixed on 21 March, the 14th day of the tabular moon, the Sunday after), the 22 March to 25 April range, and the integer algorithm.
- Selected Christian Observances (data service), US Naval Observatory, Astronomical Applications Department, years 1990 to 2070 and eight edge years fetched and read 27 September 2026. Used for: The published dates of Ash Wednesday, Palm Sunday, Good Friday, Easter, Ascension Day, Pentecost, Trinity Sunday and the First Sunday of Advent that the calendar engine is tested against.
- The Calendar of the Church Year (Book of Common Prayer, 1979), The Online Book of Common Prayer (bcponline.org), read 27 September 2026. Used for: The principal feasts, the three fixed feasts that take precedence of a Sunday (the Holy Name, the Presentation, the Transfiguration), All Saints' Day kept on the following Sunday, and feasts moved out of Holy Week and Easter Week.
- Collects: Seasons of the Year, the Season after Pentecost (Book of Common Prayer, 1979), The Online Book of Common Prayer (bcponline.org), read 27 September 2026. Used for: Proper 1 to Proper 29 named by the Sunday closest to a date (11 May to 23 November), the Last Sunday after the Epiphany as the Sunday before Ash Wednesday, and the Seventh Sunday of Easter as the Sunday after Ascension Day.
- General Norms for the Liturgical Year and the Calendar, Catholic Culture library (text of the 1969 norms), read 27 September 2026. Used for: Advent on the Sunday nearest 30 November, the Baptism of the Lord on the Sunday after 6 January, Ordinary Time of 33 or 34 weeks and where it starts and stops, and Epiphany, Ascension and Corpus Christi moved to Sundays where they are not holy days of obligation.
- Liturgical Year calendar, day pages for the Sundays of 2025-26, Catholic Culture, 53 Sundays from 30 November 2025 to 29 November 2026, read 27 September 2026. Used for: The Sunday names for the dioceses of the United States that the Ordinary Time numbering is tested against.
- Revised Common Lectionary calendar, 2025-26 and 2026-27, Vanderbilt Divinity Library, read 27 September 2026. Used for: Which proper follows Trinity Sunday in each year (Proper 5 in 2025-26, Proper 4 in 2026-27), used as a cross-check. Its reading tables are not copied.
This guide is our own summary, not a rule book. Rules are paraphrased, never quoted at length, and if this page disagrees with the current published rules, the rules win. Hymnwise is not affiliated with, endorsed by, or connected to any church, denomination, diocese, hymnal publisher, lectionary body or licensing service, including the Consultation on Common Texts, Augsburg Fortress, Church Publishing, GIA, OCP, Hope Publishing, Hymnary.org, OneLicense and CCLI.