ISO week calendar 2026
All 53 ISO weeks of 2026, with the Monday and Sunday that bound each one.
The ISO year 2026 has 53 weeks. Week 1 starts on December 29, 2025 and week 53 ends on January 3, 2027. Every row below is one ISO week, Monday through Sunday.
| ISO week | Monday | Sunday |
|---|---|---|
| Week 1 | December 29, 2025 | January 4, 2026 |
| Week 2 | January 5, 2026 | January 11, 2026 |
| Week 3 | January 12, 2026 | January 18, 2026 |
| Week 4 | January 19, 2026 | January 25, 2026 |
| Week 5 | January 26, 2026 | February 1, 2026 |
| Week 6 | February 2, 2026 | February 8, 2026 |
| Week 7 | February 9, 2026 | February 15, 2026 |
| Week 8 | February 16, 2026 | February 22, 2026 |
| Week 9 | February 23, 2026 | March 1, 2026 |
| Week 10 | March 2, 2026 | March 8, 2026 |
| Week 11 | March 9, 2026 | March 15, 2026 |
| Week 12 | March 16, 2026 | March 22, 2026 |
| Week 13 | March 23, 2026 | March 29, 2026 |
| Week 14 | March 30, 2026 | April 5, 2026 |
| Week 15 | April 6, 2026 | April 12, 2026 |
| Week 16 | April 13, 2026 | April 19, 2026 |
| Week 17 | April 20, 2026 | April 26, 2026 |
| Week 18 | April 27, 2026 | May 3, 2026 |
| Week 19 | May 4, 2026 | May 10, 2026 |
| Week 20 | May 11, 2026 | May 17, 2026 |
| Week 21 | May 18, 2026 | May 24, 2026 |
| Week 22 | May 25, 2026 | May 31, 2026 |
| Week 23 | June 1, 2026 | June 7, 2026 |
| Week 24 | June 8, 2026 | June 14, 2026 |
| Week 25 | June 15, 2026 | June 21, 2026 |
| Week 26 | June 22, 2026 | June 28, 2026 |
| Week 27 | June 29, 2026 | July 5, 2026 |
| Week 28 | July 6, 2026 | July 12, 2026 |
| Week 29 | July 13, 2026 | July 19, 2026 |
| Week 30 | July 20, 2026 | July 26, 2026 |
| Week 31 | July 27, 2026 | August 2, 2026 |
| Week 32 | August 3, 2026 | August 9, 2026 |
| Week 33 | August 10, 2026 | August 16, 2026 |
| Week 34 | August 17, 2026 | August 23, 2026 |
| Week 35 | August 24, 2026 | August 30, 2026 |
| Week 36 | August 31, 2026 | September 6, 2026 |
| Week 37 | September 7, 2026 | September 13, 2026 |
| Week 38 | September 14, 2026 | September 20, 2026 |
| Week 39 | September 21, 2026 | September 27, 2026 |
| Week 40 | September 28, 2026 | October 4, 2026 |
| Week 41 | October 5, 2026 | October 11, 2026 |
| Week 42 | October 12, 2026 | October 18, 2026 |
| Week 43 | October 19, 2026 | October 25, 2026 |
| Week 44 | October 26, 2026 | November 1, 2026 |
| Week 45 | November 2, 2026 | November 8, 2026 |
| Week 46 | November 9, 2026 | November 15, 2026 |
| Week 47 | November 16, 2026 | November 22, 2026 |
| Week 48 | November 23, 2026 | November 29, 2026 |
| Week 49 | November 30, 2026 | December 6, 2026 |
| Week 50 | December 7, 2026 | December 13, 2026 |
| Week 51 | December 14, 2026 | December 20, 2026 |
| Week 52 | December 21, 2026 | December 27, 2026 |
| Week 53 | December 28, 2026 | January 3, 2027 |
Dates are calendar dates under ISO 8601 week dating. A week belongs to the ISO year that contains its Thursday, which is why the first row can start in late December of the previous calendar year and the last row can end in early January of the next one.
About the 2026 ISO year
2026 is one of the long ISO years: it begins on a Thursday, and any ISO year that starts on a Thursday gets a 53rd week. That extra week — week 53 — runs from Monday, December 28, 2026 to Sunday, January 3, 2027, so the first three days of calendar 2027 still belong to ISO 2026. Payroll, production planning and school terms that run on week numbers all feel that extra week; if you schedule by weeks, 2026 is a year to double-check.