Does it work for past and future dates?

Yes. It works for any date, so you can check the weekday of a birthday, a historical event, or a date years ahead.

What is an ISO week number?

The ISO-8601 week number runs from 1 to 53. Week 1 is the week containing the first Thursday of the year, and weeks start on Monday.

Day of the Week Calculator

Find the weekday for any date, plus its day of the year and ISO week number.

Date

Day of the week

Tuesday

Weekday

Day of year

195

ISO week

About this calculator

Enter any date to see which day of the week it falls on. It also shows the day of the year (1–366) and the ISO-8601 week number, which is handy for scheduling and planning.

Frequently asked questions

Enter the date and the calculator instantly shows the weekday, along with the day of the year and the ISO week number.