Day of the Week Calculator

Find out what day of the week any date was, or will be — past or future, any year.

Figuring out what day of the week a specific date fell on — or will fall on — isn't something most people can do reliably in their heads beyond a week or two out in either direction, because it requires tracking exactly how many days have passed and correctly accounting for how that maps onto a repeating seven-day cycle, which becomes genuinely difficult once you're asking about a date years in the past or future.

There's actually a long history of people developing mental tricks for this exact calculation — the "Doomsday rule," a method for calculating the day of the week for any date in your head, is a real and moderately well-known memory technique, which says something about how often this specific question comes up despite how impractical it is to solve manually for most people.

This tool skips the mental arithmetic entirely: enter any date, past or future, and it tells you the exact day of the week immediately. It's useful for verifying historical dates, planning around a specific future weekday, or just satisfying curiosity about which day of the week you were born on, which is a surprisingly common thing people want to know and can't easily calculate themselves.

1. Pick a date.
2. Press Find day.
3. See the full weekday name.