ISO week calendar
Week 13 2026
ISO week 13 of 2026 runs from Monday, March 23, 2026 to Sunday, March 29, 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 13 2026
ISO week 13 of 2026 runs from Monday, March 23, 2026 to Sunday, March 29, 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, March 23, 2026
- Week ends
- Sunday, March 29, 2026
- ISO year
- 2026
- Weeks in ISO year
- 53
ISO week 13, 2026
- MonMar 23, 2026Week start
- TueMar 24, 20262026-W13
- WedMar 25, 20262026-W13
- ThuMar 26, 20262026-W13
- FriMar 27, 20262026-W13
- SatMar 28, 20262026-W13
- SunMar 29, 2026Week end
Method
Find the Monday of ISO week 1, then add seven days for each week after it.
ISO week context
Week 13 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 13 of 2026 starts on Monday, March 23, 2026.
When does this ISO week end?
Week 13 of 2026 ends on Sunday, March 29, 2026.