Week Number Calculator
Find the ISO 8601 week number, ISO year, and quarter for any date — the standard used in Europe.
ISO week number
36
Breakdown
- ISO week-numbering year
- 2,026
- Quarter
- 3
Last updated:
FAQ
Why can 1 January be week 52 or 53?
ISO weeks always start on Monday and a week belongs to the year that holds its Thursday. If New Year's Day falls on Fri–Sun, it still belongs to the last week of the previous year.
How many ISO weeks can a year have?
A year has 52 weeks normally and 53 when a leap year starts on a Thursday, or a common year starts on a Wednesday — roughly every 5–6 years.
Where is ISO week numbering used?
It is the norm across Europe for business scheduling, manufacturing, and school terms, and it is the format exchange in international agreements where US week numbering would be ambiguous.
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