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Day of the Week Calculator
Pick any date to find out which day of the week it falls on. Works for historical dates and dates far in the future, and adds the day number of the year and the ISO week number.
- Day of the year
- 284
- ISO week number
- 41
- Leap year
- No
- Weekday or weekend
- Weekend
Saved setups
Save a set of inputs you reuse — your usual rate, your loan, your room sizes — and load it back in one tap.
Your recent calculations
Results you calculate here are kept on this device so you can come back to them.
Formula
Weekday = (days since a known reference day) mod 7
How to use it
- Choose a date.
- Read the weekday.
Worked examples
July 20, 1969 — the first Moon landing
- Day of the week
- Sunday
- Weekday or weekend
- Weekend
October 11, 2026
- Day of the week
- Sunday
- Day of the year
- 284
- ISO week number
- 41
- Leap year
- No
A note on old dates
The calculator uses the Gregorian calendar throughout. Countries adopted it at different times — Catholic Europe in 1582, Britain and its colonies in 1752, Russia in 1918 — so for dates before the switch in a given country, the weekday recorded at the time may differ from the one shown here.
Questions people ask
What day of the week was I born?
Enter your date of birth. For example, May 15, 1990 was a Tuesday.
What day of the week is Christmas 2026?
Friday, December 25, 2026.
Related calculators
Age CalculatorExact age in years, months and days, plus your next birthday.Week Number CalculatorThe ISO week number for any date, with its start and end.Day of the Year CalculatorDay number of the year for any date, and days remaining.Date Calculator: Add or Subtract DaysAdd or subtract days, weeks, months and years from a date.Leap Year CalculatorIs it a leap year? Plus the next and previous ones.