What Day of the Week Was I Born?
Enter your date of birth and instantly find out which day of the week it fell on, along with a few related facts.
Why the day of the week you were born is not random trivia
Every date in history lands on exactly one day of the week, and once you know the pattern, you can work it out in your head. This calculator gives you the instant answer, but it is worth understanding the logic behind it, especially if you like party tricks.
The short version of how it is calculated
The Gregorian calendar repeats on a 400 year cycle. Mathematicians such as Karl Friedrich Gauss and later Lewis Carroll (yes, that Lewis Carroll) both published methods for working out the weekday of any date by hand, usually called "doomsday" algorithms. They rely on the fact that certain easy to remember dates always fall on the same weekday within a given year, for example 4/4, 6/6, 8/8, 10/10 and 12/12 all share a weekday every year. From there you count forward or back to your actual birth date.
This tool skips the mental math and reads the weekday straight from the calendar system built into every browser, so the answer is exact, not estimated.
Fun ways to use this
- Settle a family debate about which day someone was actually born on.
- Add a small detail to a birthday card: "born on a Tuesday" hits differently.
- Check whether your birthday and a friend's birthday fall on matching weekdays in a given year.
Frequently asked questions
How do I find out what day of the week I was born on?
Enter your date of birth above and the calculator instantly returns the exact weekday, calculated directly from the calendar rather than estimated.
Is there a way to figure this out without a calculator?
Yes, using a doomsday algorithm, a mental math trick that uses anchor dates known to fall on the same weekday every year. It takes practice, but this tool gives you the same accurate result instantly.
Do weekdays repeat in a predictable cycle?
The Gregorian calendar repeats its weekday pattern every 400 years, though within your lifetime the pattern will look irregular because of leap years shifting things by a day every four years.
Can I check the weekday for someone else's birth date, not just mine?
Yes, this works for any date of birth, past or present.