Day of the Week Calculator
What day of the week were you born? What day is a deadline 90 days from now? Enter any date to get its weekday, or count forward from today.
Day of the week
How to find the day of the week
- Enter any date, past or future.
- Read the weekday and how far the date is from today.
- Or enter a number of days to see what day it will be that many days from today.
How weekday calculation works
Each regular year shifts weekdays forward by one day, and leap years by two, because 365 days is 52 weeks plus one day. That is why your birthday moves to the next weekday each year, and skips one after February 29.
Mathematicians have mental shortcuts such as John Conway's Doomsday rule: certain easy dates like 4/4, 6/6, 8/8, 10/10 and 12/12 always fall on the same weekday within a year. For 2026 that "doomsday" is Saturday.
This calculator uses the proleptic Gregorian calendar for all dates, which matches today's calendar. Historical dates before a country switched from the Julian calendar (1752 in Britain and its colonies) may differ from records of the time.
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Frequently asked questions
What day was I born?
Enter your birth date to see the weekday.
What day will it be in 100 days?
Enter 100 in "days from today" to see the date and weekday.
Why does my birthday move each year?
365 days is 52 weeks and 1 day, so dates move forward one weekday each year (two after a leap day).
Does it work for old dates?
Yes, using the modern Gregorian calendar for all years.