Week numbers 2026
All 53 ISO weeks of 2026 with their exact dates. 2026 starts on a Thursday, has 365 days, and counts 53 calendar weeks. Week 1 begins Dec 29, 2025; week 53 ends Jan 3, 2027.
2026 has 53 ISO weeks. Week 1: Dec 29, 2025 – Jan 4, 2026. Week 53: Dec 28, 2026 – Jan 3, 2027. The current week is highlighted in the chart below. Planning ahead? Week numbers 2027 has 52 weeks, starting Monday, Jan 4, 2027.
Week number chart 2026
| Week number | From (Monday) | To (Sunday) | Month | Quarter |
|---|---|---|---|---|
| Week 1 | Dec 29, 2025 | Jan 4 | Dec / Jan | Q1 |
| Week 2 | Jan 5 | Jan 11 | January | Q1 |
| Week 3 | Jan 12 | Jan 18 | January | Q1 |
| Week 4 | Jan 19 | Jan 25 | January | Q1 |
| Week 5 | Jan 26 | Feb 1 | Jan / Feb | Q1 |
| Week 6 | Feb 2 | Feb 8 | February | Q1 |
| Week 7 | Feb 9 | Feb 15 | February | Q1 |
| Week 8 | Feb 16 | Feb 22 | February | Q1 |
| Week 9 | Feb 23 | Mar 1 | Feb / Mar | Q1 |
| Week 10 | Mar 2 | Mar 8 | March | Q1 |
| Week 11 | Mar 9 | Mar 15 | March | Q1 |
| Week 12 | Mar 16 | Mar 22 | March | Q1 |
| Week 13 | Mar 23 | Mar 29 | March | Q1 |
| Week 14 | Mar 30 | Apr 5 | Mar / Apr | Q2 |
| Week 15 | Apr 6 | Apr 12 | April | Q2 |
| Week 16 | Apr 13 | Apr 19 | April | Q2 |
| Week 17 | Apr 20 | Apr 26 | April | Q2 |
| Week 18 | Apr 27 | May 3 | Apr / May | Q2 |
| Week 19 | May 4 | May 10 | May | Q2 |
| Week 20 | May 11 | May 17 | May | Q2 |
| Week 21 | May 18 | May 24 | May | Q2 |
| Week 22 | May 25 | May 31 | May | Q2 |
| Week 23 | Jun 1 | Jun 7 | June | Q2 |
| Week 24 | Jun 8 | Jun 14 | June | Q2 |
| Week 25 | Jun 15 | Jun 21 | June | Q2 |
| Week 26 | Jun 22 | Jun 28 | June | Q2 |
| Week 27 | Jun 29 | Jul 5 | Jun / Jul | Q3 |
| Week 28 | Jul 6 | Jul 12 | July | Q3 |
| Week 29 | Jul 13 | Jul 19 | July | Q3 |
| Week 30 | Jul 20 | Jul 26 | July | Q3 |
| Week 31 | Jul 27 | Aug 2 | Jul / Aug | Q3 |
| Week 32 | Aug 3 | Aug 9 | August | Q3 |
| Week 33 | Aug 10 | Aug 16 | August | Q3 |
| Week 34 | Aug 17 | Aug 23 | August | Q3 |
| Week 35 | Aug 24 | Aug 30 | August | Q3 |
| Week 36 | Aug 31 | Sep 6 | Aug / Sep | Q3 |
| Week 37 | Sep 7 | Sep 13 | September | Q3 |
| Week 38 | Sep 14 | Sep 20 | September | Q3 |
| Week 39 | Sep 21 | Sep 27 | September | Q3 |
| Week 40 | Sep 28 | Oct 4 | Sep / Oct | Q4 |
| Week 41 | Oct 5 | Oct 11 | October | Q4 |
| Week 42 | Oct 12 | Oct 18 | October | Q4 |
| Week 43 | Oct 19 | Oct 25 | October | Q4 |
| Week 44 | Oct 26 | Nov 1 | Oct / Nov | Q4 |
| Week 45 | Nov 2 | Nov 8 | November | Q4 |
| Week 46 | Nov 9 | Nov 15 | November | Q4 |
| Week 47 | Nov 16 | Nov 22 | November | Q4 |
| Week 48 | Nov 23 | Nov 29 | November | Q4 |
| Week 49 | Nov 30 | Dec 6 | Nov / Dec | Q4 |
| Week 50 | Dec 7 | Dec 13 | December | Q4 |
| Week 51 | Dec 14 | Dec 20 | December | Q4 |
| Week 52 | Dec 21 | Dec 27 | December | Q4 |
| Week 53 | Dec 28 | Jan 3, 2027 | Dec / Jan | Q4 |
Note that week 1 of 2026 starts on Dec 29, 2025 — the last days of December 2025 belong to 2026's week 1 under ISO rules. The final week, week 53, runs into 2027: it ends on Jan 3, 2027. Weeks follow ISO 8601 (Monday start, week 1 contains January 4).
2026 week numbers by month
Which ISO weeks fall in each month of 2026, and how many weeks start (on a Monday) in that month.
| Month | Week numbers | Weeks starting | Month starts |
|---|---|---|---|
| January | 1–5 | 4 | Jan 1 (Thu) |
| February | 5–9 | 4 | Feb 1 (Sun) |
| March | 9–14 | 5 | Mar 1 (Sun) |
| April | 14–18 | 4 | Apr 1 (Wed) |
| May | 18–22 | 4 | May 1 (Fri) |
| June | 23–27 | 5 | Jun 1 (Mon) |
| July | 27–31 | 4 | Jul 1 (Wed) |
| August | 31–36 | 5 | Aug 1 (Sat) |
| September | 36–40 | 4 | Sep 1 (Tue) |
| October | 40–44 | 4 | Oct 1 (Thu) |
| November | 44–49 | 5 | Nov 1 (Sun) |
| December | 49–53 | 4 | Dec 1 (Tue) |
Holidays and key dates 2026 by week number
| Date | Day | ISO week | US week |
|---|---|---|---|
| New Year's Day | Thursday, Jan 1, 2026 | Week 1 | Week 1 |
| Valentine's Day | Saturday, Feb 14, 2026 | Week 7 | Week 7 |
| Easter Sunday | Sunday, Apr 5, 2026 | Week 14 | Week 15 |
| Mother's Day (US) | Sunday, May 10, 2026 | Week 19 | Week 20 |
| Memorial Day (US) | Monday, May 25, 2026 | Week 22 | Week 22 |
| Father's Day (US) | Sunday, Jun 21, 2026 | Week 25 | Week 26 |
| Independence Day (US) | Saturday, Jul 4, 2026 | Week 27 | Week 27 |
| Labor Day (US) | Monday, Sep 7, 2026 | Week 37 | Week 37 |
| Halloween | Saturday, Oct 31, 2026 | Week 44 | Week 44 |
| Thanksgiving (US) | Thursday, Nov 26, 2026 | Week 48 | Week 48 |
| Black Friday | Friday, Nov 27, 2026 | Week 48 | Week 48 |
| Christmas Day | Friday, Dec 25, 2026 | Week 52 | Week 52 |
| New Year's Eve | Thursday, Dec 31, 2026 | Week 53 | Week 53 |
US (Sunday-start) week numbers in 2026
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 2026, US week 1 runs from Sunday, Dec 28, 2025 to Saturday, Jan 3, 2026,
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 2026 have?
2026 has 53 ISO weeks. It is one of the rare 53-week years — the next ones are 2032, 2037.
When does week 1 of 2026 start?
Week 1 of 2026 runs from Monday, Dec 29, 2025 to Sunday, Jan 4, 2026 — it is the week containing January 4. 2026 itself begins on a Thursday.
When does the last week of 2026 end?
Week 53, the final week of 2026, runs from Dec 28, 2026 to Jan 3, 2027.
Is 2026 a leap year?
No — 2026 has 365 days, which is 52 weeks and 1 day.
What week number is Christmas 2026?
Christmas Day 2026 (Friday, Dec 25, 2026) is in ISO week 52 and US week 52. Thanksgiving (Nov 26, 2026) is in ISO week 48, and July 4 is in ISO week 27.
Do US week numbers differ from ISO week numbers in 2026?
Mostly not: from Monday to Saturday the US (Sunday-start) week number equals the ISO week number in 2026; only Sundays are one ahead.