Day of the week calculator
This calculator tells you which day of the week any date falls on, past or future. It also gives the day of the year and says whether it is, for example, the 3rd Sunday of the month. Students, genealogists and event planners use it to check dates quickly.
- Runs in your browser
- Free, no account needed
- Copy or download the result
Result
Example
Date: 1969-07-20
July 20, 1969 is a Sunday. Occurrence: the 3rd Sunday of July 1969 Day of the year: 201 of 365 ISO weekday number: 7 (Monday = 1, Sunday = 7)
How to use the day of the week calculator
- Pick a Date, from 0001-01-01 to 9999-12-31.
- Press Run.
- Read the weekday, occurrence in the month and day of the year, then use Copy result or Download.
How it works
The weekday comes from a fixed count of days in the Gregorian calendar, so it does not depend on your time zone.
Occurrence counts which matching weekday of the month it is, such as the 2nd Tuesday, and marks the last one.
The ISO weekday number uses Monday as 1 and Sunday as 7.
Dates before October 15, 1582 use Gregorian rules extended backward, which can differ from the Julian dates in old records. A note is shown for those dates.
Everything runs in your browser. Your input is not uploaded or stored.
Questions and answers
What day of the week was July 20, 1969?
It was a Sunday, the 3rd Sunday of July 1969 and day 201 of the year.
What day of the week was January 1 of year 1?
In the Gregorian calendar extended backward, it was a Monday. Historical records from that time used other calendars.
How can I tell if a date is the last Monday of the month?
Enter the date and look at the Occurrence line. It adds "and last" when no later matching weekday is in that month.