Weekmark

Calendar week · ISO 8601

Week 4, 2026

Monday 19 January – Sunday 25 January 2026

  1. Mon19Jan
  2. Tue20Jan
  3. Wed21Jan
  4. Thu22Jan
  5. Fri23Jan
  6. Sat24Jan
  7. Sun25Jan
ISO week
2026-W04
Copy as
CW4 (19–25 Jan)
Quarter
Q1 2026
Weeks in 2026
53
US week number
4

Week 4 is also written KW 4 (Kalenderwoche) or CW 4. 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 19 Jan to Saturday 24 Jan the same number: week 4.