Day of the Week Calculator
Enter any date below to instantly find out what day of the week it falls on.
How This Is Calculated
The date is mapped onto the real Gregorian calendar to determine its weekday directly, the same underlying method any calendar app uses.
A common mistake is assuming a date's weekday advances by exactly one day every single year, no exceptions. That's only true across a year that doesn't contain a February 29 between the two dates being compared — a leap day in between adds a second day of shift.
Worked example
July 4, 1976 (the US Bicentennial).
That date fell on a Sunday.
January 1, 2000 (the start of the Y2K new year).
That date fell on a Saturday — and thanks to the 400-year repeat of the Gregorian calendar, January 1, 2400 will land on a Saturday too.
Keep going
- Day of the week is often the follow-up question after landing on a new date; the add days calculator finds that resulting date from a starting point and a day count. Add Days to Date Calculator
- Whether a year is a leap year can shift which day of the week a date falls on; the leap year calculator checks that for any year you're working with. Leap Year Calculator
Frequently Asked Questions
How does this calculator find the day of the week for a date?
It uses the real Gregorian calendar to determine which weekday a given date falls on, working correctly for both past and future dates, including leap years.
How far back or forward does this work?
It works for any valid calendar date your browser's date handling supports, which in practice covers a very wide historical and future range without issue.
Why do some dates 'shift' weekdays across years?
A regular year has 365 days, which is 52 weeks plus 1 extra day, so the same calendar date shifts forward one weekday each year. Leap years add a second shift, which is why weekday patterns aren't simply repeating every year.
Does the weekday pattern ever repeat exactly?
Yes — every 400 years. The Gregorian calendar fits exactly 146,097 days into every 400-year span (146,097 ÷ 7 = 20,871, with no remainder), so any date's weekday in one 400-year cycle matches its weekday 400 years later. January 1, 2000 was a Saturday, and January 1, 2400 will be a Saturday too.
Does this work for dates before the 1500s?
This calculator applies today's Gregorian calendar rules to every date, including ones before it existed. Most of the world didn't adopt the Gregorian calendar until 1582 or later (England and its colonies switched in 1752), so historical records from before a given country's adoption date were kept in the older Julian calendar and won't match this calculator's weekday without a manual correction.
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- Days Until Calculator — Date Calculators
- Add Days to Date Calculator — Date Calculators