How many weeks are in a year?
That is why "52 weeks" is right for planning and payroll, but the calendar never lines up exactly: the extra day (or two) is why each year starts one weekday later than the last, and why a numbered-week calendar sometimes needs a week 53.
52 or 53 numbered weeks?
Under ISO 8601 week numbering — Monday-start weeks, week 1 contains 4 January — a year has 52 weeks, except when 1 January falls on a Thursday (or on a Wednesday in a leap year), which gives 53. Roughly one year in five or six has 53. 2026 has 53.
Every year, 2022–2032
| Year | Days | Weeks (exact) | ISO weeks | 1 January is a | Weekdays (Mon–Fri) |
|---|---|---|---|---|---|
| 2022 | 365 | 52.14 | 52 | Saturday | 260 |
| 2023 | 365 | 52.14 | 52 | Sunday | 260 |
| 2024 | 366 | 52.29 | 52 | Monday | 262 |
| 2025 | 365 | 52.14 | 52 | Wednesday | 261 |
| 2026 | 365 | 52.14 | 53 | Thursday | 261 |
| 2027 | 365 | 52.14 | 52 | Friday | 261 |
| 2028 | 366 | 52.29 | 52 | Saturday | 260 |
| 2029 | 365 | 52.14 | 52 | Monday | 261 |
| 2030 | 365 | 52.14 | 52 | Tuesday | 261 |
| 2031 | 365 | 52.14 | 52 | Wednesday | 261 |
| 2032 | 366 | 52.29 | 53 | Thursday | 262 |
Weeks in a year for planning
| Calendar weeks | 52 (53 in some years by ISO count) |
| Weeks for salary and payroll | 52 weekly pay periods · 26 biweekly · 24 semi-monthly · details |
| Working weeks | 52 minus your holidays and vacation — typically 46–48 in the US · calculator |
| Weeks in a month | 4.35 on average (4 weeks + 2–3 days) · by month |
| School year (US) | 36 weeks (180 days) |
Method
Days per year: 365, or 366 when the year is divisible by 4 and not by 100, or divisible by 400. Weeks = days ÷ 7. ISO week count follows ISO 8601-1:2019 §4.2.2 (a week belongs to the year that contains its Thursday). Weekday counts are computed by walking every date of the year.