What week is it?
Today's week number according to ISO 8601 (weeks start on Monday; week 1 contains the year's first Thursday) – the standard used across Europe.
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How to use it
- The big number shows the current week.
- Pick any date to see its week number, or enter a year and week to see its Monday–Sunday dates.
- Scroll the table to see every week of the selected year.
Last checked: October 2026 · Based on: ISO 8601. Found a mistake? Use the form below – we fix confirmed errors and update the date.
Frequently asked questions
How are ISO week numbers defined?
Weeks run Monday to Sunday. Week 1 is the week that contains the first Thursday of the year (equivalently, January 4th). A year therefore has 52 or 53 weeks.
Why do some years have 53 weeks?
When a year starts on a Thursday, or a leap year starts on a Wednesday, it has 53 ISO weeks.
Is the US week number the same?
Not always – US calendars often start weeks on Sunday and count week 1 as the week with January 1st. This tool uses ISO 8601.