Week numbers 2026
All 53 ISO weeks of 2026 with their date ranges, alongside the US numbering for the same weeks. Under ISO 8601, week 1 of 2026 begins on 29 Dec 2025.
| Week | ISO 8601 (Monday start) | US (Sunday start) |
|---|---|---|
| 1 | 29 Dec to 4 Jan | 28 Dec to 3 Jan |
| 2 | 5 Jan to 11 Jan | 4 Jan to 10 Jan |
| 3 | 12 Jan to 18 Jan | 11 Jan to 17 Jan |
| 4 | 19 Jan to 25 Jan | 18 Jan to 24 Jan |
| 5 | 26 Jan to 1 Feb | 25 Jan to 31 Jan |
| 6 | 2 Feb to 8 Feb | 1 Feb to 7 Feb |
| 7 | 9 Feb to 15 Feb | 8 Feb to 14 Feb |
| 8 | 16 Feb to 22 Feb | 15 Feb to 21 Feb |
| 9 | 23 Feb to 1 Mar | 22 Feb to 28 Feb |
| 10 | 2 Mar to 8 Mar | 1 Mar to 7 Mar |
| 11 | 9 Mar to 15 Mar | 8 Mar to 14 Mar |
| 12 | 16 Mar to 22 Mar | 15 Mar to 21 Mar |
| 13 | 23 Mar to 29 Mar | 22 Mar to 28 Mar |
| 14 | 30 Mar to 5 Apr | 29 Mar to 4 Apr |
| 15 | 6 Apr to 12 Apr | 5 Apr to 11 Apr |
| 16 | 13 Apr to 19 Apr | 12 Apr to 18 Apr |
| 17 | 20 Apr to 26 Apr | 19 Apr to 25 Apr |
| 18 | 27 Apr to 3 May | 26 Apr to 2 May |
| 19 | 4 May to 10 May | 3 May to 9 May |
| 20 | 11 May to 17 May | 10 May to 16 May |
| 21 | 18 May to 24 May | 17 May to 23 May |
| 22 | 25 May to 31 May | 24 May to 30 May |
| 23 | 1 Jun to 7 Jun | 31 May to 6 Jun |
| 24 | 8 Jun to 14 Jun | 7 Jun to 13 Jun |
| 25 | 15 Jun to 21 Jun | 14 Jun to 20 Jun |
| 26 | 22 Jun to 28 Jun | 21 Jun to 27 Jun |
| 27 | 29 Jun to 5 Jul | 28 Jun to 4 Jul |
| 28 | 6 Jul to 12 Jul | 5 Jul to 11 Jul |
| 29 | 13 Jul to 19 Jul | 12 Jul to 18 Jul |
| 30 | 20 Jul to 26 Jul | 19 Jul to 25 Jul |
| 31 | 27 Jul to 2 Aug | 26 Jul to 1 Aug |
| 32 | 3 Aug to 9 Aug | 2 Aug to 8 Aug |
| 33 | 10 Aug to 16 Aug | 9 Aug to 15 Aug |
| 34 | 17 Aug to 23 Aug | 16 Aug to 22 Aug |
| 35 | 24 Aug to 30 Aug | 23 Aug to 29 Aug |
| 36 | 31 Aug to 6 Sep | 30 Aug to 5 Sep |
| 37 | 7 Sep to 13 Sep | 6 Sep to 12 Sep |
| 38 | 14 Sep to 20 Sep | 13 Sep to 19 Sep |
| 39 | 21 Sep to 27 Sep | 20 Sep to 26 Sep |
| 40 | 28 Sep to 4 Oct | 27 Sep to 3 Oct |
| 41 | 5 Oct to 11 Oct | 4 Oct to 10 Oct |
| 42 | 12 Oct to 18 Oct | 11 Oct to 17 Oct |
| 43 | 19 Oct to 25 Oct | 18 Oct to 24 Oct |
| 44 | 26 Oct to 1 Nov | 25 Oct to 31 Oct |
| 45 | 2 Nov to 8 Nov | 1 Nov to 7 Nov |
| 46 | 9 Nov to 15 Nov | 8 Nov to 14 Nov |
| 47 | 16 Nov to 22 Nov | 15 Nov to 21 Nov |
| 48 | 23 Nov to 29 Nov | 22 Nov to 28 Nov |
| 49 | 30 Nov to 6 Dec | 29 Nov to 5 Dec |
| 50 | 7 Dec to 13 Dec | 6 Dec to 12 Dec |
| 51 | 14 Dec to 20 Dec | 13 Dec to 19 Dec |
| 52 | 21 Dec to 27 Dec | 20 Dec to 26 Dec |
| 53 | 28 Dec to 3 Jan | - |
See it on a calendar. Open the week calendar for three years of week rows side by side, with your own leave, travel and deadlines marked on them. Free, no sign-up.
Why two systems disagree
Everyone agrees a year has weeks. Nobody agrees which one is week 1, and that is where the two numbers come from.
ISO 8601, used across Europe and by most software, starts weeks on Monday and gives week 1 to the first week with four or more of its days in the new year. That is usually described as "the week containing the first Thursday", which is the same rule said differently: Thursday is the fourth day of a Monday-start week.
The US convention starts weeks on Sunday and gives week 1 to whatever week holds 1 January. It is easier to explain and it produces a 53rd week far more often.
The two can differ by a full week for the same date, which is exactly the sort of thing that goes unnoticed until two reports disagree at a year end.
Other years: 2024 · 2025 · 2027 · 2028 · 2029 · what week is it now