Week 21 of 2026
May 18 – May 24, 2026
| Monday | May 18, 2026 | Mon · week starts |
| Tuesday | May 19, 2026 | |
| Wednesday | May 20, 2026 | |
| Thursday | May 21, 2026 | |
| Friday | May 22, 2026 | |
| Saturday | May 23, 2026 | |
| Sunday | May 24, 2026 | Sun · week ends |
All weeks of 2026
2026 is an ISO year with 53 weeks.
About ISO week 21 of 2026
ISO 8601 weeks start on Monday and end on Sunday. Week 21 of 2026 begins on Monday, May 18, 2026 and ends on Sunday, May 24, 2026. 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 2026?
Week 21 of 2026 spans May 18 – May 24, 2026: Monday May 18 through Sunday May 24.
When is week 21 of 2026?
Week 21 of 2026 started 162 days ago, on Monday, May 18, 2026.
Why does 2026 have 53 weeks?
2026 is a "long" ISO year with 53 weeks. This happens when the year starts on a Thursday, or on a Wednesday in a leap year — the extra days spill into a 53rd numbered week.