Week 21 in 2025
Week 21 of 2025 begins on May 19, 2025 and ends on May 25, 2025. It covers days 139 to 145 of the year and falls in quarter 2.
Weeks since this week: 73
Week 21 of 2025 at a glance
| Starts (Monday) | May 19, 2025 |
|---|---|
| Ends (Sunday) | May 25, 2025 |
| US week (Sunday to Saturday) | 21 (May 18, 2025) |
| Month | May |
| Quarter | Q2 |
| Days of the year | 139–145 |
| Year completed at the end of this week | 39.7% |
| Weeks left in 2025 after this week | 31 |
| Weeks in 2025 | 52 |
| Even or odd week | Odd |
Calendar for May 2025
Download Calendar in printable A4 PDF
(US version) (EU/ISO Version)
All Weeks in 2025:
Past & Future Week Number 21:
US and ISO week numbers
In the US system, where weeks start on Sunday and week 1 is the week that contains 1 January, this is week 21 of 2025. It runs from May 18, 2025 to May 24, 2025.
Even and odd weeks
Week 21 is an odd week. Even and odd week numbers are used for alternating schedules such as shift rotas, school timetables, custody arrangements and waste collection.
Week 21 in other years
| From | To | |
|---|---|---|
| Week 21 in 2023 | May 22, 2023 | May 28, 2023 |
| Week 21 in 2024 | May 20, 2024 | May 26, 2024 |
| Week 21 in 2026 | May 18, 2026 | May 24, 2026 |
| Week 21 in 2027 | May 24, 2027 | May 30, 2027 |
How week numbers are counted
Most of the world numbers weeks according to the ISO 8601 standard. A week starts on Monday, and week 1 is the week that contains the first Thursday of the year, which is always the week that contains 4 January.
Week 1 of 2025 began on December 30, 2024. 2025 has 52 ISO weeks.
Because of this rule, the first days of January can belong to the last week of the previous year, and the last days of December can belong to week 1 of the next year.
In the United States, weeks usually start on Sunday and week 1 is the week that contains 1 January, so the US week number can differ from the ISO week number.
Find the week number of a date
Frequently Asked Questions (FAQ)
When does week 21 of 2025 start and end?
Week 21 of 2025 starts on May 19, 2025 and ends on May 25, 2025 (ISO 8601, Monday to Sunday).
Which month is week 21 of 2025 in?
Week 21 of 2025 is in May.
What dates are in week 21 of 2025?
May 19, 2025, May 20, 2025, May 21, 2025, May 22, 2025, May 23, 2025, May 24, 2025, and May 25, 2025
How many weeks does 2025 have?
2025 has 52 ISO weeks.
Is week 21 an even or odd week?
Week 21 is an odd week.
What is the US week number for this week?
In the US system, where weeks start on Sunday and week 1 is the week that contains 1 January, this is week 21 of 2025. It runs from May 18, 2025 to May 24, 2025.