ISO week calendar
Week 52 2026
ISO week 52 of 2026 runs from Monday, December 21, 2026 to Sunday, December 27, 2026.
Date Time Encyclopedia answer, with calculation details and assumptions below.
ISO weeks start on Monday and end on Sunday. Week 1 is the week containing the first Thursday of the ISO week-numbering year.
Snapshot
Week 52 2026
ISO week 52 of 2026 runs from Monday, December 21, 2026 to Sunday, December 27, 2026.
ISO weeks start on Monday and end on Sunday. Week 1 is the week containing the first Thursday of the ISO week-numbering year.
- Week starts
- Monday, December 21, 2026
- Week ends
- Sunday, December 27, 2026
- ISO year
- 2026
- Weeks in ISO year
- 53
ISO week 52, 2026
- MonDec 21, 2026Week start
- TueDec 22, 20262026-W52
- WedDec 23, 20262026-W52
- ThuDec 24, 20262026-W52
- FriDec 25, 20262026-W52
- SatDec 26, 20262026-W52
- SunDec 27, 2026Week end
Method
Find the Monday of ISO week 1, then add seven days for each week after it.
ISO week context
Week 52 2026 uses the ISO week-date system: weeks start Monday, end Sunday, and week 1 is tied to the first Thursday of the ISO year.
Compare nearby ISO weeks
Adjacent week pages help verify handoffs between reporting periods, sprints, payroll periods, and weekly plans.
Related Lookups
FAQ
When does this ISO week start?
Week 52 of 2026 starts on Monday, December 21, 2026.
When does this ISO week end?
Week 52 of 2026 ends on Sunday, December 27, 2026.