Week 21 of 2025
May 19 – May 25, 2025
| Monday | May 19, 2025 | Mon · week starts |
| Tuesday | May 20, 2025 | |
| Wednesday | May 21, 2025 | |
| Thursday | May 22, 2025 | |
| Friday | May 23, 2025 | |
| Saturday | May 24, 2025 | |
| Sunday | May 25, 2025 | Sun · week ends |
All weeks of 2025
2025 is an ISO year with 52 weeks.
About ISO week 21 of 2025
ISO 8601 weeks start on Monday and end on Sunday. Week 21 of 2025 begins on Monday, May 19, 2025 and ends on Sunday, May 25, 2025. Week numbering follows the international standard: week 1 of a year is the week containing the first Thursday of January, which is why some calendar dates near January 1st belong to the previous or next ISO year.
The ISO week system is the standard for business reporting across Europe and much of the world. The US convention differs: weeks start on Sunday and week 1 contains January 1st, so US week numbers can be one ahead of or behind ISO numbers near year boundaries.
Frequently asked questions
What dates are in week 21 of 2025?
Week 21 of 2025 spans May 19 – May 25, 2025: Monday May 19 through Sunday May 25.
When is week 21 of 2025?
Week 21 of 2025 started 526 days ago, on Monday, May 19, 2025.
Why does 2025 have 52 weeks?
2025 has the usual 52 ISO weeks. Only years starting on a Thursday (or a Wednesday in a leap year) get a 53rd week.