- Instant answersResults update as you type.
- Private by designRuns in your browser. Nothing is sent.
- Share, print or citeCopy a link with your numbers.
Examples
| Date | Weekday |
|---|---|
| June 6, 1944 (D-Day) | Tuesday |
| September 11, 2001 | Tuesday |
| January 1, 2000 | Saturday |
The calculator uses the proleptic Gregorian calendar, so very old dates (before a country adopted the Gregorian calendar) follow modern rules.
How the weekday is found
The calculator counts the exact number of days between your date and a known reference date and takes the remainder after dividing by 7. That is equivalent to Zeller's congruence, the formula people use to do this by hand. For example, January 1, 2027 is a Friday: January 1, 2026 is a Thursday, and 2026 has 365 days, which is 52 weeks and 1 day.
Calendars that repeat
The Gregorian calendar repeats exactly every 400 years, because 400 years is 146,097 days, or exactly 20,871 weeks. Single years repeat more often: 2026 uses the same calendar as 2015 and 2037, so a 2015 calendar works for 2026.
Related tools
- Days until any dateCountdown in days and weeks
- Date differenceDays between two dates
- Add or subtract daysFind a date N days away
- Age calculatorExact age in years, months, days
Frequently asked questions
What day was I born?
Enter your birth date above to see the weekday.
Does it work for future dates?
Yes, any date from year 1 onward.
What day of the week was I born?
Enter your birth date above; the answer covers any date in the Gregorian calendar.
Why do old dates sometimes disagree with history books?
Countries switched from the Julian to the Gregorian calendar at different times, for example Britain in 1752. This tool always uses Gregorian rules.