ISO week calendar
Week 42 2026
ISO week 42 of 2026 runs from Monday, October 12, 2026 to Sunday, October 18, 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 42 2026
ISO week 42 of 2026 runs from Monday, October 12, 2026 to Sunday, October 18, 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, October 12, 2026
- Week ends
- Sunday, October 18, 2026
- ISO year
- 2026
- Weeks in ISO year
- 53
ISO week 42, 2026
- MonOct 12, 2026Week start
- TueOct 13, 20262026-W42
- WedOct 14, 20262026-W42
- ThuOct 15, 20262026-W42
- FriOct 16, 20262026-W42
- SatOct 17, 20262026-W42
- SunOct 18, 2026Week end
Method
Find the Monday of ISO week 1, then add seven days for each week after it.
ISO week context
Week 42 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 42 of 2026 starts on Monday, October 12, 2026.
When does this ISO week end?
Week 42 of 2026 ends on Sunday, October 18, 2026.