Week 21, 2025

1. Mon19May
2. Tue20May
3. Wed21May
4. Thu22May
5. Fri23May
6. Sat24May
7. Sun25May

ISO week

2025-W21

Copy as

CW21 (19–25 May)

Quarter

Q2 2025

Weeks in 2025

52

US week number

21

Week 21 is also written KW 21 (Kalenderwoche) or CW 21. 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 May to Saturday 24 May the same number: week 21.