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Day of the week for any date

Today is Wednesday. Enter any date to see which day of the week it was or will be, with the working shown so you can check it by hand.

Day of the week calculator

Wednesday

Wednesday, November 11, 2026 is today.

Day of the year
315
ISO week
2026-W46-3
Days from today
0
Show the working

Pick a date to see Zeller’s congruence and the Doomsday rule worked through for it.

Weekdays of dates in calendar history

DateWeekdayWhat happened
October 4, 1582 (Julian)ThursdayLast day of the Julian calendar in Italy, Spain, Portugal and Poland (USNO)
October 15, 1582FridayFirst day of the Gregorian calendar (USNO)
September 2, 1752 (Julian)WednesdayLast Julian day in Britain and its colonies (Calendar (New Style) Act 1750)
September 14, 1752ThursdayFirst Gregorian day in Britain and its colonies (Calendar (New Style) Act 1750)
January 1, 2000SaturdayJ2000.0, the astronomers’ reference epoch (at noon) (USNO)
February 29, 2000TuesdayThe first February 29 in a century year since 1600: 2000 is divisible by 400 (USNO)
January 1, 2017SundayThe most recent leap second was added just before this day began (UTC) (IERS Bulletin C)
June 17, 2021ThursdayJuneteenth became a federal holiday (Pub. L. 117-17) (5 U.S.C. 6103 notes)

Coming up: Christmas Day is Friday, December 25, 2026, and New Year’s Day is Friday, January 1, 2027.

Working it out by hand: Zeller’s congruence

Christian Zeller published this formula in the 1880s. It turns a Gregorian date into a number from 0 to 6, where 0 is Saturday:

h = (q + ⌊13(m+1)/5⌋ + K + ⌊K/4⌋ + ⌊J/4⌋ + 5J) mod 7

Here q is the day of the month, m the month with January and February counted as months 13 and 14 of the previous year, K the last two digits of that year and J its first two digits. The brackets ⌊ ⌋ mean “round down”.

Worked example: January 1, 2000

January counts as month 13 of 1999, so q = 1, m = 13, K = 99 and J = 19. The six terms are 1, ⌊13 × 14 / 5⌋ = 36, 99, ⌊99 / 4⌋ = 24, ⌊19 / 4⌋ = 4 and 5 × 19 = 95. They add up to 259, and 259 mod 7 = 0, which is Saturday. January 1, 2000 was indeed a Saturday.

The Doomsday rule, for mental arithmetic

John Horton Conway’s method uses the fact that some easy-to-remember dates always share a weekday within a year, the year’s “doomsday”: 4/4, 6/6, 8/8, 10/10 and 12/12, 5/9 and 9/5, 7/11 and 11/7, the last day of February, March 14, and July 4. January 3 is a doomsday in common years and January 4 in leap years.

  1. Century anchor. 1700s Sunday, 1800s Friday, 1900s Wednesday, 2000s Tuesday; the pattern repeats every 400 years.
  2. Year’s doomsday. Take the last two digits of the year, divide by 12, and add the quotient, the remainder and the remainder divided by 4 (rounded down). Count that many days on from the anchor.
  3. Your date. Count from the nearest doomsday in the same month to your date.

Worked example: July 4, 1776

The anchor for the 1700s is Sunday. For 76: 76 ÷ 12 = 6 remainder 4, and 4 ÷ 4 = 1, so count 6 + 4 + 1 = 11 days on from Sunday: 1776’s doomsday was a Thursday. July 4 is itself a doomsday, so the Declaration of Independence was adopted on a Thursday.

Dates before 1582, and before 1752 in Britain and America

Both methods above, and the calculator, use the Gregorian calendar extended backwards, called the proleptic Gregorian calendar; ISO 8601 uses it too. But people living before the reform wrote their dates in the Julian calendar, whose dates ran 10 days behind in 1582 and 11 days behind by 1752. The U.S. Naval Observatory treats dates up to October 4, 1582 as Julian and dates from October 15, 1582 as Gregorian; the weekday sequence ran on without a break (USNO).

Britain and its colonies kept the Julian calendar until September 1752 (Calendar (New Style) Act 1750), so a date in an English or colonial American document from before then is usually Julian, sometimes with two years for dates between January 1 and March 25. George Washington’s birthday is the classic case: he would have given it as February 11, 1731, and it is now given as February 22, 1732 (National Park Service). For dates before the switch, the calculator gives the weekday under both calendars.

Questions about days of the week

What day of the week was I born?

Enter your date of birth in the calculator. If you were born before 1752 in Britain or its colonies, or before 1582 in Catholic Europe, your birth date was probably written in the Julian calendar; the calculator shows that reading too.

Does the weekday cycle ever skip?

No. The seven-day week has run without a break through every calendar reform. When ten days were dropped in October 1582, Thursday the 4th was followed by Friday the 15th; when Britain dropped eleven in 1752, Wednesday the 2nd was followed by Thursday the 14th.

Why does my birthday fall one weekday later each year?

365 days is 52 weeks and 1 day, so a date moves one weekday later each year, and two when February 29 falls in between. The whole Gregorian calendar repeats every 400 years, which is exactly 146,097 days, or 20,871 weeks.

Which calendar does the calculator use?

The Gregorian calendar, extended back before 1582 (the “proleptic” Gregorian calendar, which ISO 8601 allows for earlier dates by agreement between the parties). For dates before the switch, it also gives the weekday of the same written date in the Julian calendar.

For today’s weekday and date in every format, see today’s date; for a whole year at once, the calendar.

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