Week 40 1991: September 30–6, 1991
Week 40 starts on Monday, September 30, 1991 and ends on Sunday, October 6, 1991.
Quick answer
Week 40 of 1991 is the seven-day ISO week from September 30, 1991 to October 6, 1991. ISO weeks always run from Monday to Sunday.
Use week 40 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 40 of 1991?
The dates are September 30, 1991 through October 6, 1991.
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 40 of 1991 (Sep 30–Oct 6, 1991)” so the week-year and date range are both clear.