How to use it
This week
The current ISO week shows at the top, with the US week number too.
Week of a date
Pick any date to get its week number and day of the year.
Dates of a week
Type a year and week number to see its seven days.
ISO weeks of 2026 and 2027
Each week runs Monday to Sunday. 2026 has 53 ISO weeks, 2027 has 52.
| Week | 2026 | 2027 |
|---|---|---|
| 1 | Dec 29 2025 – Jan 4 | Jan 4 – Jan 10 |
| 2 | Jan 5 – Jan 11 | Jan 11 – Jan 17 |
| 3 | Jan 12 – Jan 18 | Jan 18 – Jan 24 |
| 4 | Jan 19 – Jan 25 | Jan 25 – Jan 31 |
| 5 | Jan 26 – Feb 1 | Feb 1 – Feb 7 |
| 6 | Feb 2 – Feb 8 | Feb 8 – Feb 14 |
| 7 | Feb 9 – Feb 15 | Feb 15 – Feb 21 |
| 8 | Feb 16 – Feb 22 | Feb 22 – Feb 28 |
| 9 | Feb 23 – Mar 1 | Mar 1 – Mar 7 |
| 10 | Mar 2 – Mar 8 | Mar 8 – Mar 14 |
| 11 | Mar 9 – Mar 15 | Mar 15 – Mar 21 |
| 12 | Mar 16 – Mar 22 | Mar 22 – Mar 28 |
| 13 | Mar 23 – Mar 29 | Mar 29 – Apr 4 |
| 14 | Mar 30 – Apr 5 | Apr 5 – Apr 11 |
| 15 | Apr 6 – Apr 12 | Apr 12 – Apr 18 |
| 16 | Apr 13 – Apr 19 | Apr 19 – Apr 25 |
| 17 | Apr 20 – Apr 26 | Apr 26 – May 2 |
| 18 | Apr 27 – May 3 | May 3 – May 9 |
| 19 | May 4 – May 10 | May 10 – May 16 |
| 20 | May 11 – May 17 | May 17 – May 23 |
| 21 | May 18 – May 24 | May 24 – May 30 |
| 22 | May 25 – May 31 | May 31 – Jun 6 |
| 23 | Jun 1 – Jun 7 | Jun 7 – Jun 13 |
| 24 | Jun 8 – Jun 14 | Jun 14 – Jun 20 |
| 25 | Jun 15 – Jun 21 | Jun 21 – Jun 27 |
| 26 | Jun 22 – Jun 28 | Jun 28 – Jul 4 |
| 27 | Jun 29 – Jul 5 | Jul 5 – Jul 11 |
| 28 | Jul 6 – Jul 12 | Jul 12 – Jul 18 |
| 29 | Jul 13 – Jul 19 | Jul 19 – Jul 25 |
| 30 | Jul 20 – Jul 26 | Jul 26 – Aug 1 |
| 31 | Jul 27 – Aug 2 | Aug 2 – Aug 8 |
| 32 | Aug 3 – Aug 9 | Aug 9 – Aug 15 |
| 33 | Aug 10 – Aug 16 | Aug 16 – Aug 22 |
| 34 | Aug 17 – Aug 23 | Aug 23 – Aug 29 |
| 35 | Aug 24 – Aug 30 | Aug 30 – Sep 5 |
| 36 | Aug 31 – Sep 6 | Sep 6 – Sep 12 |
| 37 | Sep 7 – Sep 13 | Sep 13 – Sep 19 |
| 38 | Sep 14 – Sep 20 | Sep 20 – Sep 26 |
| 39 | Sep 21 – Sep 27 | Sep 27 – Oct 3 |
| 40 | Sep 28 – Oct 4 | Oct 4 – Oct 10 |
| 41 | Oct 5 – Oct 11 | Oct 11 – Oct 17 |
| 42 | Oct 12 – Oct 18 | Oct 18 – Oct 24 |
| 43 | Oct 19 – Oct 25 | Oct 25 – Oct 31 |
| 44 | Oct 26 – Nov 1 | Nov 1 – Nov 7 |
| 45 | Nov 2 – Nov 8 | Nov 8 – Nov 14 |
| 46 | Nov 9 – Nov 15 | Nov 15 – Nov 21 |
| 47 | Nov 16 – Nov 22 | Nov 22 – Nov 28 |
| 48 | Nov 23 – Nov 29 | Nov 29 – Dec 5 |
| 49 | Nov 30 – Dec 6 | Dec 6 – Dec 12 |
| 50 | Dec 7 – Dec 13 | Dec 13 – Dec 19 |
| 51 | Dec 14 – Dec 20 | Dec 20 – Dec 26 |
| 52 | Dec 21 – Dec 27 | Dec 27 – Jan 2 2028 |
| 53 | Dec 28 – Jan 3 2027 | — |
FAQ
What week number is it today?
It’s shown at the top of this page and follows your device’s date, in both the ISO and the US system.
What’s the difference between ISO and US week numbers?
ISO weeks start on Monday and week 1 has the year’s first Thursday. US weeks start on Sunday and week 1 has January 1, so the two can differ by one.
How many weeks are in a year?
52 weeks and a day or two, so an ISO year has 52 or 53 weeks; the US system can have 53 or 54 because the first and last weeks can be partial.
Why is January 1 sometimes in week 52 or 53?
ISO gives each week to the year of its Thursday, so if January 1 falls on a Friday, Saturday or Sunday it belongs to the last week of the previous year.