ISO Week Calendar

Week Calculator

Current week: W21 of 2026 (53 weeks total)
Date → Week Number

Enter a date to find its ISO week number

Week Number → Date Range

Enter a year and week number to find the date range

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Today24. May 2026isW21W21 / 53

Frequently Asked Questions

What is the current week number?
The current week is week 21 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.