Day of the Week Calculator

How does this calculator work?

Enter any supported calendar date. The calculator converts it to a stable UTC calendar ordinal, then determines its weekday without using time-of-day or time-zone offsets.

Quick example

July 20, 1969 was a Sunday. You can check that historical date or look up the weekday of your next anniversary.

Frequently asked questions

Are historical dates always accurate?

The calculation uses the modern Gregorian calendar extended backward. Some countries used different calendars historically.

Can it calculate future dates?

Yes. Enter any date from 1900 through 2100.