Which Years Have 53 Weeks?
Direct answer
2026 has 53 ISO weeks. Most ISO years have 52 weeks, but some have 53 depending on how weekdays align with January 1.
Nearby ISO years
| Year | ISO weeks | Has Week 53? |
|---|---|---|
| 2021 | 52 | No |
| 2022 | 52 | No |
| 2023 | 52 | No |
| 2024 | 52 | No |
| 2025 | 52 | No |
| 2026 | 53 | Yes |
| 2027 | 52 | No |
| 2028 | 52 | No |
| 2029 | 52 | No |
| 2030 | 52 | No |
| 2031 | 52 | No |
Why does 2026 have 53 weeks?
2026 starts on a Thursday. Under ISO rules, that alignment creates 53 full ISO week numbers in the ISO week-year.
View the 2026 calendar or open Week 53, 2026.
ISO 53-week rule
An ISO year has 53 weeks when January 1 falls on Thursday, or when January 1 falls on Wednesday in a leap year. Another way to check the same rule is to look at December 31: if it falls on Thursday, or Friday in a leap year, the ISO year has Week 53.
Planning edge cases
| ISO week | Date range | Planning note |
|---|---|---|
| 2026-W01 | 2025-12-29 to 2026-01-04 | The ISO year starts before calendar year 2026. |
| 2026-W53 | 2026-12-28 to 2027-01-03 | The final ISO week crosses into calendar year 2027. |