Week 39 of 2025
September 22 – September 28, 2025
| Monday | September 22, 2025 | Mon · week starts |
| Tuesday | September 23, 2025 | |
| Wednesday | September 24, 2025 | |
| Thursday | September 25, 2025 | |
| Friday | September 26, 2025 | |
| Saturday | September 27, 2025 | |
| Sunday | September 28, 2025 | Sun · week ends |
All weeks of 2025
2025 is an ISO year with 52 weeks.
About ISO week 39 of 2025
ISO 8601 weeks start on Monday and end on Sunday. Week 39 of 2025 begins on Monday, September 22, 2025 and ends on Sunday, September 28, 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 39 of 2025?
Week 39 of 2025 spans September 22 – September 28, 2025: Monday September 22 through Sunday September 28.
When is week 39 of 2025?
Week 39 of 2025 started 400 days ago, on Monday, September 22, 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.