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Date & Time
Day of the Week Calculator
Find the weekday of any date — plus day of year, week number and leap year.
Day of the week
—
What day it falls on.
| Day number of year | — |
|---|---|
| ISO week number | — |
| Leap year? | — |
| Date | — |
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Enter your figures above to see the step-by-step working.
Everything computed client-sideEverything computed client-side — nothing leaves this page
How the Day of the Week Calculator Works
Enter any date — past or future — and this calculator tells you which day of the week it falls on, working directly from the calendar so leap years and month lengths are handled correctly. It also shows the day’s number within the year, its ISO week number, and whether the year is a leap year.
It’s handy for finding the weekday of a birthday, a historical date or a future deadline, and for anyone working with week numbers in planning and payroll.
day of week = calendar weekday of the given date
Frequently Asked Questions
What day of the week was I born?
Enter your birth date and the calculator returns the weekday, using the actual calendar so it’s exact for any year.
What is an ISO week number?
A standard numbering of weeks 1–53 where weeks start on Monday and week 1 contains the year’s first Thursday. The calculator shows it for your date.
How is a leap year determined?
A year is a leap year if it’s divisible by 4, except century years, which must be divisible by 400. So 2000 was a leap year but 1900 wasn’t.
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