ISO Week Calendar

Week Calculator

Current week: W37 of 2026 (53 weeks total)
Date → Week Number

Enter a date to find its ISO week number

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Enter a year and week number to find the date range

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Today9. September 2026isW37W37 / 53

Frequently Asked Questions

What is the current week number?
The current week is week 37 of 2026 (ISO 8601 standard).
How are ISO week numbers calculated?
ISO weeks start on Monday and end on Sunday. Week 1 is the week containing the first Thursday of the year.
How many weeks are in a year?
Most years have 52 ISO weeks. Some years (like 2026) have 53 weeks.