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What Week of the Year Is It?
Today's week number, plus a lookup for any date.
ISO 8601 week
42
Mon, Oct 12, 2026 – Sun, Oct 18, 2026
Week number of any date
Week 42
Friday, October 16, 2026
Weeks of 2026 (53 ISO weeks)
| Week | Monday | Sunday |
|---|---|---|
| 1 | Mon, Dec 29, 2025 | Sun, Jan 4 |
| 2 | Mon, Jan 5 | Sun, Jan 11 |
| 3 | Mon, Jan 12 | Sun, Jan 18 |
| 4 | Mon, Jan 19 | Sun, Jan 25 |
| 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 |
| 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 |
| 23 | Mon, Jun 1 | Sun, Jun 7 |
| 24 | Mon, Jun 8 | Sun, Jun 14 |
| 25 | Mon, Jun 15 | Sun, Jun 21 |
| 26 | Mon, Jun 22 | Sun, Jun 28 |
| 27 | Mon, Jun 29 | Sun, Jul 5 |
| 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 |
| 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 |
| 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 |
| 47 | Mon, Nov 16 | Sun, Nov 22 |
| 48 | Mon, Nov 23 | Sun, Nov 29 |
| 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 |
| 53 | Mon, Dec 28 | Sun, Jan 3, 2027 |
ISO week numbers vs US week numbers
ISO 8601 (used in Europe, most of Asia, and many business systems) starts weeks on Monday. Week 1 is the week that contains the year's first Thursday, which is the same as the week containing January 4. A year has 52 or 53 ISO weeks, and early January days can belong to the last week of the previous year.
The US system starts weeks on Sunday and counts the week containing January 1 as week 1, so it can differ from ISO by one. Example: Friday, October 16, 2026 is ISO week 42 (Monday Oct 12 – Sunday Oct 18), written 2026-W42-5, and US week 42 as well.
Frequently asked questions
Which years have 53 weeks?
Years that start on a Thursday, and leap years that start on a Wednesday, have 53 ISO weeks. 2020 and 2026 are examples; the next is 2032.
What week number does Excel use?
=ISOWEEKNUM(date) gives the ISO week. =WEEKNUM(date) uses the US Sunday-start system by default.
Can January 1 be in week 52 or 53?
Yes. In ISO numbering, if January 1 falls on a Friday, Saturday, or Sunday, it belongs to the last week of the previous year.
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