Day of the Week Calculator
Enter any date to find out what day of the week it falls on.
Last updated: September 21, 2026
Frequently asked questions
What day of the week was January 1, 2000?
Saturday - a widely known reference date, useful for verifying day-of-week calculations.
How do you calculate the day of the week for any date?
The most common method is Zeller's congruence, a formula that uses the day, month, and year (with January and February treated as months 13 and 14 of the previous year) to directly compute the day of the week without needing a calendar lookup.
Does this work for dates far in the past or future?
Yes - it uses the proleptic Gregorian calendar, meaning it applies today's calendar rules consistently to any date, even before the Gregorian calendar was actually adopted in 1582. Historical dates recorded under the Julian calendar may differ from this calculation.
Why does knowing the day of the week matter for old or future dates?
It's useful for genealogy research, verifying historical records, planning far-future events, or just satisfying curiosity about what day a birthday, anniversary, or historical event actually fell on.
What day of the week will January 1, 2050 fall on?
Enter that date above - the calculator applies the proleptic Gregorian calendar to compute it directly, working just as reliably for future dates decades out as it does for the present or the past.
Does the day-of-week calculation change depending on my time zone?
No - the result depends only on the calendar date you enter, not on time zone, since a given calendar date corresponds to exactly one weekday regardless of where you are.
Is this the same as asking 'what day of the week does Christmas fall on'?
Yes - enter December 25 with any year and this tool returns exactly that: the weekday a specific recurring date falls on for that particular year.