ISO week

Week 40 of 2026

2026-W40September 28 – October 4, 2026Monday through Sunday

Mon28September Tue29September Wed30September Thu1October Fri2October Sat3October Sun4October

ISO notation2026-W40

Start09-28-2026

End10-04-2026

ISO weeks in year53

All seven days in Week 40

MondaySeptember 28, 2026 TuesdaySeptember 29, 2026 WednesdaySeptember 30, 2026 ThursdayOctober 1, 2026 FridayOctober 2, 2026 SaturdayOctober 3, 2026 SundayOctober 4, 2026

Week 40 context

ISO Week 40 of 2026 runs from September 28, 2026 through October 4, 2026. ISO weeks always contain seven days and start on Monday.

Nearby weeks

Week 37 Week 38 Week 39 Week 40 Week 41 Week 42 Week 43

All weeks in 2026 →