Current week number
What week is it?
The current ISO week number, and every week of the year with its start and end dates. Pick another year to plan ahead.
Reference
ISO weeks by year
| Year | Weeks | Week 1 starts | Last week ends |
|---|---|---|---|
| 2026 | 53 | Monday, December 29, 2025 | Sunday, January 3, 2027 |
| 2027 | 52 | Monday, January 4, 2027 | Sunday, January 2, 2028 |
| 2028 | 52 | Monday, January 3, 2028 | Sunday, December 31, 2028 |
| 2029 | 52 | Monday, January 1, 2029 | Sunday, December 30, 2029 |
| 2030 | 52 | Monday, December 31, 2029 | Sunday, December 29, 2030 |
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FAQ
Week number, answered
Anything we have not answered here, ask us directly. A senior engineer replies.
What week is it?
The figure at the top of the week list is this week’s ISO week number, worked out from your device’s date. The week it belongs to is highlighted in the list.
How are week numbers counted?
Under ISO 8601, weeks start on Monday and week 1 is the week that contains the year’s first Thursday, which is also the week that contains 4 January. Most of Europe and many businesses use this system.
Does a year have 52 or 53 weeks?
Most years have 52 ISO weeks. A year has 53 when it starts on a Thursday, or on a Wednesday in a leap year. 2026 has 53 weeks and 2027 has 52.
Why does 1 January sometimes belong to week 52 or 53?
When 1 January falls on a Friday, Saturday or Sunday, that week has fewer than four days in the new year, so it counts as the last week of the year before.
Do US calendars number weeks the same way?
Not always. Some US calendars start weeks on Sunday and call the week with 1 January week 1, so their numbers can be one off from ISO numbers. This tool uses ISO 8601.
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