Day of the Week Finder
Find the day of the week for any date, past or future, with the calendar facts behind it.
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- ISO date
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- Day of year
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- ISO week
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- ISO weekday no.
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- Leap year
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- Position in month
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- From today
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- Doomsday of that year
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Same date in other years
| Year | Date | Day of the week |
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29 February only exists in leap years, so only leap years are listed.
Dates before 15 October 1582 are shown in the proleptic Gregorian calendar — the calendar in use at the time was the Julian one, whose weekday for the same written date differs.
How it works
Pick any date — a birthday, a historic event, a future deadline — and the weekday appears instantly. The calculation uses the proleptic Gregorian calendar (the same rule set as Zeller's congruence and the Doomsday algorithm): every year divisible by 4 is a leap year, except century years, which must also be divisible by 400. That is why 1900 had no 29 February but 2000 did. The Apollo 11 moon landing on 20 July 1969, for example, was a Sunday; 1 January 2000 was a Saturday.
Alongside the weekday you get the ISO-8601 week number (weeks start on Monday and week 1 is the week containing the first Thursday of the year, so 1 January 2000 belongs to week 52 of 1999), the ISO weekday number from 1 = Monday to 7 = Sunday, the day of the year, whether the year is a leap year, which occurrence of that weekday it is in the month, and how many days separate the date from today. The Doomsday row shows the year's anchor weekday — the day that 4/4, 6/6, 8/8, 10/10, 12/12 and the last day of February all fall on — which is the key to working out weekdays in your head.
The table lists the same day and month across the following years, so you can see when a birthday next lands on a weekend. Everything runs in your browser in UTC, so daylight-saving switches can never shift the answer by a day, and the dates you enter are never uploaded, logged or tracked. No sign-up, no ads.
Frequently asked questions
What day of the week was I born?
Enter your date of birth and the finder shows the weekday immediately, along with the day of the year and the ISO week it fell in.
Does it work for dates before 1900?
Yes. The calculation uses the proleptic Gregorian calendar, so historical dates are handled the same way modern ones are.
What is the doomsday anchor?
The doomsday is the weekday shared by several easy-to-remember dates in a given year, such as 4/4 and 6/6. It is the basis of Conway's mental method for working out weekdays without a calendar.