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What Week Is It?

See today's week number, the day of the year and how many days are left. Pick any date, switch between US and ISO 8601 week numbering, and browse the dates of every week of the year.

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ISO 8601 weeks start on Monday and week 1 is the week with the year's first Thursday, so the first days of January can belong to the last week of the previous year.

Week numbers for 2026

  1. Week 1Dec 28 – Jan 3
  2. Week 2Jan 4 – Jan 10
  3. Week 3Jan 11 – Jan 17
  4. Week 4Jan 18 – Jan 24
  5. Week 5Jan 25 – Jan 31
  6. Week 6Feb 1 – Feb 7
  7. Week 7Feb 8 – Feb 14
  8. Week 8Feb 15 – Feb 21
  9. Week 9Feb 22 – Feb 28
  10. Week 10Mar 1 – Mar 7
  11. Week 11Mar 8 – Mar 14
  12. Week 12Mar 15 – Mar 21
  13. Week 13Mar 22 – Mar 28
  14. Week 14Mar 29 – Apr 4
  15. Week 15Apr 5 – Apr 11
  16. Week 16Apr 12 – Apr 18
  17. Week 17Apr 19 – Apr 25
  18. Week 18Apr 26 – May 2
  19. Week 19May 3 – May 9
  20. Week 20May 10 – May 16
  21. Week 21May 17 – May 23
  22. Week 22May 24 – May 30
  23. Week 23May 31 – Jun 6
  24. Week 24Jun 7 – Jun 13
  25. Week 25Jun 14 – Jun 20
  26. Week 26Jun 21 – Jun 27
  27. Week 27Jun 28 – Jul 4
  28. Week 28Jul 5 – Jul 11
  29. Week 29Jul 12 – Jul 18
  30. Week 30Jul 19 – Jul 25
  31. Week 31Jul 26 – Aug 1
  32. Week 32Aug 2 – Aug 8
  33. Week 33Aug 9 – Aug 15
  34. Week 34Aug 16 – Aug 22
  35. Week 35Aug 23 – Aug 29
  36. Week 36Aug 30 – Sep 5
  37. Week 37Sep 6 – Sep 12
  38. Week 38Sep 13 – Sep 19
  39. Week 39Sep 20 – Sep 26
  40. Week 40Sep 27 – Oct 3
  41. Week 41Oct 4 – Oct 10
  42. Week 42Oct 11 – Oct 17
  43. Week 43Oct 18 – Oct 24
  44. Week 44Oct 25 – Oct 31
  45. Week 45Nov 1 – Nov 7
  46. Week 46Nov 8 – Nov 14
  47. Week 47Nov 15 – Nov 21
  48. Week 48Nov 22 – Nov 28
  49. Week 49Nov 29 – Dec 5
  50. Week 50Dec 6 – Dec 12
  51. Week 51Dec 13 – Dec 19
  52. Week 52Dec 20 – Dec 26
  53. Week 53Dec 27 – Jan 2

How to use

  1. Today's week number is shown when the page opens; pick another date if needed.
  2. Choose US (weeks start Sunday) or ISO 8601 (weeks start Monday).
  3. Browse the week list for any year.

Options explained

US week numbers
Weeks start on Sunday and week 1 contains 1 January — the default for Excel's WEEKNUM.
ISO 8601
Used across Europe and much of Asia. Weeks start on Monday and week 1 contains the first Thursday of the year, giving 52 or 53 weeks.

Examples (ISO 8601)

Date Week
1 January 2026 Week 1 of 2026
26 September 2026 Week 39 of 2026
1 January 2027 Week 53 of 2026

Frequently asked questions

Why can 1 January be in week 53?

Under ISO 8601, week 1 must contain the year's first Thursday. If 1 January falls on a Friday, Saturday or Sunday, those days belong to the previous year's last week.

How many weeks does 2026 have?

53 ISO weeks, because 2026 starts on a Thursday. In US numbering 31 December 2026 is in week 53 as well.

How do I get ISO week numbers in Excel?

Use ISOWEEKNUM. WEEKNUM defaults to the US system.

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