How do I find the day of the week for a date?

Pick the month, day and year and the weekday appears.

What is an ISO week number?

Weeks start on Monday, and week 1 is the week containing the first Thursday of January.

It uses the Gregorian calendar, which was adopted at different times in different countries.

Choose any date, past or future, to see the weekday, the ISO week number and the day of the year.

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Find the weekday for any date, past or future, along with the day of the year, ISO week number and days remaining in the year.

Uses the fixed 400-year Gregorian weekday cycle. ISO week: week 1 contains the first Thursday of January; weeks start Monday.

Common questions about Day of the Week Calculator

We use the standard published formula for this calculation, and we show the working so you can check it.

Spotted a mistake? Tell us and we'll check it within a few days. See how we check our calculators.