Week numbers 2025
All 52 ISO weeks of 2025 with their exact dates. 2025 starts on a Wednesday, has 365 days, and counts 52 calendar weeks. Week 1 begins Dec 30, 2024; week 52 ends Dec 28, 2025.
2025 has 52 ISO weeks. Week 1: Dec 30 – Jan 5, 2025. Week 52: Dec 22 – Dec 28, 2025.
Week number chart 2025
| Week number | From (Monday) | To (Sunday) | Month | Quarter |
|---|---|---|---|---|
| Week 1 | Dec 30, 2024 | Jan 5 | Dec / Jan | Q1 |
| Week 2 | Jan 6 | Jan 12 | January | Q1 |
| Week 3 | Jan 13 | Jan 19 | January | Q1 |
| Week 4 | Jan 20 | Jan 26 | January | Q1 |
| Week 5 | Jan 27 | Feb 2 | Jan / Feb | Q1 |
| Week 6 | Feb 3 | Feb 9 | February | Q1 |
| Week 7 | Feb 10 | Feb 16 | February | Q1 |
| Week 8 | Feb 17 | Feb 23 | February | Q1 |
| Week 9 | Feb 24 | Mar 2 | Feb / Mar | Q1 |
| Week 10 | Mar 3 | Mar 9 | March | Q1 |
| Week 11 | Mar 10 | Mar 16 | March | Q1 |
| Week 12 | Mar 17 | Mar 23 | March | Q1 |
| Week 13 | Mar 24 | Mar 30 | March | Q1 |
| Week 14 | Mar 31 | Apr 6 | Mar / Apr | Q2 |
| Week 15 | Apr 7 | Apr 13 | April | Q2 |
| Week 16 | Apr 14 | Apr 20 | April | Q2 |
| Week 17 | Apr 21 | Apr 27 | April | Q2 |
| Week 18 | Apr 28 | May 4 | Apr / May | Q2 |
| Week 19 | May 5 | May 11 | May | Q2 |
| Week 20 | May 12 | May 18 | May | Q2 |
| Week 21 | May 19 | May 25 | May | Q2 |
| Week 22 | May 26 | Jun 1 | May / Jun | Q2 |
| Week 23 | Jun 2 | Jun 8 | June | Q2 |
| Week 24 | Jun 9 | Jun 15 | June | Q2 |
| Week 25 | Jun 16 | Jun 22 | June | Q2 |
| Week 26 | Jun 23 | Jun 29 | June | Q2 |
| Week 27 | Jun 30 | Jul 6 | Jun / Jul | Q3 |
| Week 28 | Jul 7 | Jul 13 | July | Q3 |
| Week 29 | Jul 14 | Jul 20 | July | Q3 |
| Week 30 | Jul 21 | Jul 27 | July | Q3 |
| Week 31 | Jul 28 | Aug 3 | Jul / Aug | Q3 |
| Week 32 | Aug 4 | Aug 10 | August | Q3 |
| Week 33 | Aug 11 | Aug 17 | August | Q3 |
| Week 34 | Aug 18 | Aug 24 | August | Q3 |
| Week 35 | Aug 25 | Aug 31 | August | Q3 |
| Week 36 | Sep 1 | Sep 7 | September | Q3 |
| Week 37 | Sep 8 | Sep 14 | September | Q3 |
| Week 38 | Sep 15 | Sep 21 | September | Q3 |
| Week 39 | Sep 22 | Sep 28 | September | Q3 |
| Week 40 | Sep 29 | Oct 5 | Sep / Oct | Q4 |
| Week 41 | Oct 6 | Oct 12 | October | Q4 |
| Week 42 | Oct 13 | Oct 19 | October | Q4 |
| Week 43 | Oct 20 | Oct 26 | October | Q4 |
| Week 44 | Oct 27 | Nov 2 | Oct / Nov | Q4 |
| Week 45 | Nov 3 | Nov 9 | November | Q4 |
| Week 46 | Nov 10 | Nov 16 | November | Q4 |
| Week 47 | Nov 17 | Nov 23 | November | Q4 |
| Week 48 | Nov 24 | Nov 30 | November | Q4 |
| Week 49 | Dec 1 | Dec 7 | December | Q4 |
| Week 50 | Dec 8 | Dec 14 | December | Q4 |
| Week 51 | Dec 15 | Dec 21 | December | Q4 |
| Week 52 | Dec 22 | Dec 28 | December | Q4 |
Note that week 1 of 2025 starts on Dec 30, 2024 — the last days of December 2024 belong to 2025's week 1 under ISO rules. Weeks follow ISO 8601 (Monday start, week 1 contains January 4).
2025 week numbers by month
Which ISO weeks fall in each month of 2025, and how many weeks start (on a Monday) in that month.
| Month | Week numbers | Weeks starting | Month starts |
|---|---|---|---|
| January | 1–5 | 4 | Jan 1 (Wed) |
| February | 5–9 | 4 | Feb 1 (Sat) |
| March | 9–14 | 5 | Mar 1 (Sat) |
| April | 14–18 | 4 | Apr 1 (Tue) |
| May | 18–22 | 4 | May 1 (Thu) |
| June | 22–27 | 5 | Jun 1 (Sun) |
| July | 27–31 | 4 | Jul 1 (Tue) |
| August | 31–35 | 4 | Aug 1 (Fri) |
| September | 36–40 | 5 | Sep 1 (Mon) |
| October | 40–44 | 4 | Oct 1 (Wed) |
| November | 44–48 | 4 | Nov 1 (Sat) |
| December | 49–52, 1 (2026) | 5 | Dec 1 (Mon) |
Holidays and key dates 2025 by week number
| Date | Day | ISO week | US week |
|---|---|---|---|
| New Year's Day | Wednesday, Jan 1, 2025 | Week 1 | Week 1 |
| Valentine's Day | Friday, Feb 14, 2025 | Week 7 | Week 7 |
| Easter Sunday | Sunday, Apr 20, 2025 | Week 16 | Week 17 |
| Mother's Day (US) | Sunday, May 11, 2025 | Week 19 | Week 20 |
| Memorial Day (US) | Monday, May 26, 2025 | Week 22 | Week 22 |
| Father's Day (US) | Sunday, Jun 15, 2025 | Week 24 | Week 25 |
| Independence Day (US) | Friday, Jul 4, 2025 | Week 27 | Week 27 |
| Labor Day (US) | Monday, Sep 1, 2025 | Week 36 | Week 36 |
| Halloween | Friday, Oct 31, 2025 | Week 44 | Week 44 |
| Thanksgiving (US) | Thursday, Nov 27, 2025 | Week 48 | Week 48 |
| Black Friday | Friday, Nov 28, 2025 | Week 48 | Week 48 |
| Christmas Day | Thursday, Dec 25, 2025 | Week 52 | Week 52 |
| New Year's Eve | Wednesday, Dec 31, 2025 | Week 1 (2026) | Week 53 |
US (Sunday-start) week numbers in 2025
The chart above uses ISO 8601 (Monday start). US calendars, Outlook in US locale and Excel's default
WEEKNUM() count differently: weeks start on Sunday and week 1 is the week containing
January 1. In 2025, US week 1 runs from Sunday, Dec 29, 2024 to Saturday, Jan 4, 2025,
and the year has 53 US week numbers (the last one is partial).
For Monday–Saturday the US week number is the same as the ISO week number; on Sundays it is one higher (because the US week has already rolled over). To convert any single date, use the week number calculator — it shows both systems. Background: week start conventions.
Other years
Frequently asked questions
How many weeks does 2025 have?
2025 has 52 ISO weeks. Like most years it has 52 numbered weeks; the nearest 53-week years are 2020, 2026, 2032.
When does week 1 of 2025 start?
Week 1 of 2025 runs from Monday, Dec 30, 2024 to Sunday, Jan 5, 2025 — it is the week containing January 4. 2025 itself begins on a Wednesday.
When does the last week of 2025 end?
Week 52, the final week of 2025, runs from Dec 22, 2025 to Dec 28, 2025.
Is 2025 a leap year?
No — 2025 has 365 days, which is 52 weeks and 1 day.
What week number is Christmas 2025?
Christmas Day 2025 (Thursday, Dec 25, 2025) is in ISO week 52 and US week 52. Thanksgiving (Nov 27, 2025) is in ISO week 48, and July 4 is in ISO week 27.
Do US week numbers differ from ISO week numbers in 2025?
Mostly not: from Monday to Saturday the US (Sunday-start) week number equals the ISO week number in 2025; only Sundays are one ahead.