Week numbers 2026
When does week 1 of 2026 start? On December 29, 2025 (ISO 8601).
53ISO weeks in 2026
Mon, Dec 29week 1 starts
Sun, Jan 3week 53 ends
2026 has 53 ISO weeks: week 53 runs from December 28 to January 3, 2027. These are ISO 8601 week numbers, used in Europe, most of the world and by Excel's ISOWEEKNUM: weeks start on Monday and week 1 is the week with the year's first Thursday. In the US, many calendars start weeks on Sunday and count the week containing January 1 as week 1, so the US number can be one higher.
| Week | Monday | Sunday | US federal holidays |
|---|---|---|---|
| 1 | Mon, Dec 29 | Sun, Jan 4 | New Year's Day |
| 2 | Mon, Jan 5 | Sun, Jan 11 | |
| 3 | Mon, Jan 12 | Sun, Jan 18 | |
| 4 | Mon, Jan 19 | Sun, Jan 25 | Martin Luther King Jr. Day |
| 5 | Mon, Jan 26 | Sun, Feb 1 | |
| 6 | Mon, Feb 2 | Sun, Feb 8 | |
| 7 | Mon, Feb 9 | Sun, Feb 15 | |
| 8 | Mon, Feb 16 | Sun, Feb 22 | Washington's Birthday |
| 9 | Mon, Feb 23 | Sun, Mar 1 | |
| 10 | Mon, Mar 2 | Sun, Mar 8 | |
| 11 | Mon, Mar 9 | Sun, Mar 15 | |
| 12 | Mon, Mar 16 | Sun, Mar 22 | |
| 13 | Mon, Mar 23 | Sun, Mar 29 | |
| 14 | Mon, Mar 30 | Sun, Apr 5 | |
| 15 | Mon, Apr 6 | Sun, Apr 12 | |
| 16 | Mon, Apr 13 | Sun, Apr 19 | |
| 17 | Mon, Apr 20 | Sun, Apr 26 | |
| 18 | Mon, Apr 27 | Sun, May 3 | |
| 19 | Mon, May 4 | Sun, May 10 | |
| 20 | Mon, May 11 | Sun, May 17 | |
| 21 | Mon, May 18 | Sun, May 24 | |
| 22 | Mon, May 25 | Sun, May 31 | Memorial Day |
| 23 | Mon, Jun 1 | Sun, Jun 7 | |
| 24 | Mon, Jun 8 | Sun, Jun 14 | |
| 25 | Mon, Jun 15 | Sun, Jun 21 | Juneteenth National Independence Day |
| 26 | Mon, Jun 22 | Sun, Jun 28 | |
| 27 | Mon, Jun 29 | Sun, Jul 5 | Independence Day (observed), Independence Day |
| 28 | Mon, Jul 6 | Sun, Jul 12 | |
| 29 | Mon, Jul 13 | Sun, Jul 19 | |
| 30 | Mon, Jul 20 | Sun, Jul 26 | |
| 31 | Mon, Jul 27 | Sun, Aug 2 | |
| 32 | Mon, Aug 3 | Sun, Aug 9 | |
| 33 | Mon, Aug 10 | Sun, Aug 16 | |
| 34 | Mon, Aug 17 | Sun, Aug 23 | |
| 35 | Mon, Aug 24 | Sun, Aug 30 | |
| 36 | Mon, Aug 31 | Sun, Sep 6 | |
| 37 | Mon, Sep 7 | Sun, Sep 13 | Labor Day |
| 38 | Mon, Sep 14 | Sun, Sep 20 | |
| 39 | Mon, Sep 21 | Sun, Sep 27 | |
| 40 | Mon, Sep 28 | Sun, Oct 4 | |
| 41 | Mon, Oct 5 | Sun, Oct 11 | |
| 42 | Mon, Oct 12 | Sun, Oct 18 | Columbus Day |
| 43 | Mon, Oct 19 | Sun, Oct 25 | |
| 44 | Mon, Oct 26 | Sun, Nov 1 | |
| 45 | Mon, Nov 2 | Sun, Nov 8 | |
| 46 | Mon, Nov 9 | Sun, Nov 15 | Veterans Day |
| 47 | Mon, Nov 16 | Sun, Nov 22 | |
| 48 | Mon, Nov 23 | Sun, Nov 29 | Thanksgiving Day |
| 49 | Mon, Nov 30 | Sun, Dec 6 | |
| 50 | Mon, Dec 7 | Sun, Dec 13 | |
| 51 | Mon, Dec 14 | Sun, Dec 20 | |
| 52 | Mon, Dec 21 | Sun, Dec 27 | Christmas Day |
| 53 | Mon, Dec 28 | Sun, Jan 3 | New Year's Day |
Week number in Excel and Google Sheets
- ISO week (Monday start)=ISOWEEKNUM(A1)
- US week (Sunday start)=WEEKNUM(A1)
- Current ISO week=ISOWEEKNUM(TODAY())
Questions
How many weeks are in 2026?
2026 has 53 ISO weeks: week 53 runs from December 28 to January 3, 2027.
When does week 1 of 2026 start?
On December 29, 2025 (ISO 8601).
- Current week number
- Week numbers 2025
- Week numbers 2027
- 2026 calendar
Federal holidays follow the US Office of Personnel Management (OPM) list; dates are calculated, not estimated.