Week 39 2025: September 22–28, 2025
Week 39 starts on Monday, September 22, 2025 and ends on Sunday, September 28, 2025.
Quick answer
Week 39 of 2025 is the seven-day ISO week from September 22, 2025 to September 28, 2025. ISO weeks always run from Monday to Sunday.
Use week 39 in professional planning
This permanent week reference can be used in project plans, payroll notes, weekly reports, production schedules and deadline documents. Share the week number together with the ISO year and exact date range to avoid ambiguity around New Year.
For calculations that span more than one week, use the weeks between dates calculator. For work schedules, compare the same range with the business days calculator or open the project timeline calculator.
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FAQ
What are the dates for week 39 of 2025?
The dates are September 22, 2025 through September 28, 2025.
What day does this week start?
It starts on Monday.
What day does this week end?
It ends on Sunday.
How should I write this week in a report?
Use “ISO week 39 of 2025 (Sep 22–Sep 28, 2025)” so the week-year and date range are both clear.