GoToCalculator.netQuick search.../

Week Number Calculator

Real-time Engine

Choose a date to find its ISO 8601 week number and the dates covered by that Monday-to-Sunday week.

Find an ISO week number

Leave blank to use today's local date.

Result

Choose a date, then calculate.

Weeks Left in the YearSee how many full weeks and days remain in the current year.Weeks From Today CalculatorFind the calendar date a chosen number of weeks before or after today.Date CalculatorAdd or subtract days, weeks, months, or years from any calendar date.
AdvertisementReserved Display SlotZero CLS placement

How ISO week numbers work

ISO 8601 weeks begin on Monday. Week 1 is the week containing the year's first Thursday, so dates near New Year's Day can belong to the previous or next ISO week-year.

ISO week example

January 1 can be in week 52 or 53 of the preceding ISO week-year, depending on the weekday.

What to know

  • The result includes the ISO week-year.
  • The Monday and Sunday dates for the week are shown.

Frequently Asked Questions

Does the week start on Sunday?

No. ISO weeks begin on Monday and end on Sunday.

Why can the ISO year differ from the calendar year?

The first and last few calendar dates of a year can belong to an adjacent ISO week-year.

Found a problem with this calculator? Report an issue.