Does 2025 have 53 ISO weeks?
No — 2025 has the ordinary 52. January 1, 2025 is a Wednesday and 2025 is not a leap year.
Worked from a fixed input so the numbers stay put: 2025. Try your own on the home page.
ISO year 2025 has 52 weeks. (January 1, 2025 is a Wednesday, and 2025 is not a leap year.)
- ISO year
- 2025
- Weeks in that ISO year
- 52
Other examples
Not a general calendar or scheduling tool, and it does not know about business fiscal-year or retail 4-4-5 week numbering, which are different systems that also call themselves "week numbers." It has no concept of time of day or timezone — it operates on calendar dates only. Not for US-style "week of the month" or non-ISO week-start conventions (e.g. Sunday-start week numbering used by some US calendars).