Week 38 2025: September 15–21, 2025
Week 38 starts on Monday, September 15, 2025 and ends on Sunday, September 21, 2025.
Quick answer
Week 38 of 2025 is the seven-day ISO week from September 15, 2025 to September 21, 2025. ISO weeks always run from Monday to Sunday.
Use week 38 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.
Weeks around week 38
Browse priority week calendars
Continue with a planning tool
FAQ
What are the dates for week 38 of 2025?
The dates are September 15, 2025 through September 21, 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 38 of 2025 (Sep 15–Sep 21, 2025)” so the week-year and date range are both clear.