Weekmark

Calendar week · ISO 8601

Week 1, 2025

Monday 30 December 2024 – Sunday 5 January 2025

  1. Mon30Dec
  2. Tue31Dec
  3. Wed1Jan
  4. Thu2Jan
  5. Fri3Jan
  6. Sat4Jan
  7. Sun5Jan
ISO week
2025-W01
Copy as
CW1 (30 Dec – 5 Jan)
Quarter
Q1 2025
Weeks in 2025
52
US week number
1

Week 1 is also written KW 1 (Kalenderwoche) or CW 1. ISO weeks start on Monday, and week 1 is the week with the year’s first Thursday. US calendars start weeks on Sunday and count the week with 1 January as week 1, so they give Monday 30 Dec to Saturday 4 Jan the same number: week 1.