What day was it?
Any date, any year — the weekday, on tap.
How it works
Every date maps to exactly one weekday. Under the hood we ask JavaScript's Date object which uses the proleptic Gregorian calendar back to year 1 — the same calendar system most digital systems use. Because the answer only cares about which day of the week the date falls on, timezone and daylight-saving quirks don't matter here. This is useful for spotting patterns in birthdays across a family, planning a wedding, or answering pub-quiz questions.
Frequently asked
Does it work for dates before 1900?open
Yes, back to 1 January 1 CE using the proleptic Gregorian calendar. Historical dates before the Gregorian reform (1582) use the Gregorian calendar 'as if it had always existed', which may differ from what a historian would give.
Does it handle leap years?open
Yes — including the '400-year rule' that skips leap years in century years not divisible by 400.
Which day starts the week?open
The tool reports the weekday name only, so start-of-week convention doesn't matter here. Locales that use Sunday-first or Monday-first will still see the same name.