How many weeks are in a year?
52
weeks and 1 day in a 365-day year
That is 52.14 weeks. A leap year has 52 weeks and 2 days (52.29 weeks). In the ISO week calendar, 2026 has 53 weeks and today is in week 40.
Why 52 weeks and 1 day
A normal year has 365 days. Divide by 7 and you get 52 weeks with 1 day left over. A leap year has 366 days, so 2 days are left over. Over the full 400-year cycle of the Gregorian calendar, the average year is 365.2425 days, or 52.1775 weeks.
That spare day is why a date moves one weekday later each year, and two after 29 February. 2026 began on a Thursday, 2027 begins on a Friday, and 2028 on a Saturday.
Which years have 53 weeks?
The UK uses ISO 8601 week numbers: weeks run Monday to Sunday, and week 1 is the week with the year's first Thursday in it. A year has 53 ISO weeks when it starts on a Thursday, or when it is a leap year that starts on a Wednesday. That happens 71 times in every 400 years.
| Year | Starts on | ISO weeks | Week 53 |
|---|---|---|---|
| 2025 | Wednesday | 52 | – |
| 2026 | Thursday | 53 | Mon 28 Dec 2026 to Sun 3 Jan 2027 |
| 2027 | Friday | 52 | – |
| 2028 (leap) | Saturday | 52 | – |
| 2029 | Monday | 52 | – |
| 2030 | Tuesday | 52 | – |
| 2031 | Wednesday | 52 | – |
| 2032 (leap) | Thursday | 53 | Mon 27 Dec 2032 to Sun 2 Jan 2033 |
After 2032, the next 53-week year is 2037. Week 1 of 2027 starts on Monday 4 January 2027, because 1 to 3 January still belong to week 53 of 2026. Check today's week number or see the weeks laid out in the 2026 calendar.
53 paydays, and other effects
Whichever weekday a year starts on occurs 53 times in it. In a leap year, the first two weekdays do. 2026 has 53 Thursdays. 2027 starts and ends on a Friday, so it has 53 Fridays, and anyone paid weekly on a Friday gets 53 paydays in calendar year 2027.
Businesses that run a 52-week accounting year fall about a day and a quarter behind the calendar each year, so they add a 53rd week every five or six years to catch up.
Weeks in a month
An average month has 30.44 days, or 4.35 weeks. A 31-day month is 4 weeks and 3 days, a 30-day month 4 weeks and 2 days, and February exactly 4 weeks (4 weeks and 1 day in a leap year). To find the date a number of weeks ahead, use weeks from today.
Frequently asked questions
Are there 52 or 53 weeks in a year?
Every year has 52 full weeks plus 1 or 2 days. In the ISO week numbering used in the UK, most years have 52 weeks, but years that start on a Thursday, and leap years that start on a Wednesday, have 53.
How many weeks are in 2026?
2026 has 52 weeks and 1 day. It starts on a Thursday, so it has 53 ISO weeks. Week 53 runs from Monday 28 December 2026 to Sunday 3 January 2027.
How many weeks are in 2027?
2027 has 52 weeks and 1 day, and 52 ISO weeks. Week 1 starts on Monday 4 January 2027 and week 52 ends on Sunday 2 January 2028.
How many working weeks are in a year?
For a full-time worker on a 5-day week, 52.14 weeks minus the statutory 5.6 weeks of paid holiday leaves about 46.5 working weeks. The 5.6 weeks can include bank holidays.
When is the next year with 53 weeks?
After 2026, the next years with 53 ISO weeks are 2032 and 2037.