September 28 – October 4, 2026
MonTueWedThuFriSatSun
Week 1 contains the first Thursday of the year.ISO guide →Date → week number
October 4, 2026: What week number?
Sunday, October 4, 2026ISO Week 402026-W40
ISO Week 40 runs from September 28, 2026 to October 4, 2026.
ISO vs US-style week numbers
The same date can have different week numbers
ISO weeks start on Monday. The simplified US-style system starts on Sunday and counts the week containing January 1 as Week 1.
October 4–10, 2026
SunMonTueWedThuFriSat
Week 1 contains January 1.US-style guide →ISO weekWeek 40
US-style weekWeek 41
WeekdaySunday
QuarterQ4
Day of year277 / 365
ISO weekday7 / 7
October 2026
Date context
Sunday, October 4, 2026 is day 277 of 2026 and belongs to ISO Week 40.
This ISO week crosses a month boundary: it starts in September and ends in October.
Distance from today
How long until October 4, 2026?
Days48
Full weeks6
Remaining days6
October 4, 2026 is 48 days from today, equal to 6 full weeks and 6 days.