ISO week reference
Week 40 2025: September 29, 2025 – October 5, 2025
Exact Monday-to-Sunday dates for 2025-W40. Use this week as a calendar reference, open it in the planner, or view it in the full 2025 ISO calendar.
Week40
ISO year2025
Weekdays5
QuarterQ3
ISO reference2025-W40
Starts
Ends
Length7 days
Exact dates
Dates in week 40
ISO weeks run Monday through Sunday.
MonSep 292025
TueSep 302025
WedOct 12025
ThuOct 22025
FriOct 32025
SatOct 42025
SunOct 52025
Use this week
Open Week 40 Planner
Turn these dates into a plan
Open a private weekly planner already set to September 29, 2025 – October 5, 2025, then add priorities, deadlines, meetings and hourly work blocks.