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How many weeks are in a year?

The short answer, and why some years have 53 weeks.

In short

A year has 52 weeks and 1 day (365 days); a leap year has 52 weeks and 2 days. Counted in ISO weeks, most years have 52 and some have 53: 2020, 2026, 2032 and 2037. 2027 has 52.

Weeks per year, 2024 to 2038

YearDaysISO weeksStarts on
202436652Monday
202536552Wednesday
202636553Thursday
202736552Friday
202836652Saturday
202936552Monday
203036552Tuesday
203136552Wednesday
203236653Thursday
203336552Saturday
203436552Sunday
203536552Monday
203636652Tuesday
203736553Thursday
203836552Friday

Years with 53 ISO weeks between 2000 and 2050: 2004, 2009, 2015, 2020, 2026, 2032, 2037, 2043, 2048.

Questions

How many work weeks are in a year?

52, with 260 or 261 weekdays (262 in some leap years). Minus the 11 federal holidays that leaves about 250 working days; 2027 has 249.

How many weeks are in a month?

About 4.35 on average (30.44 days ÷ 7). February has exactly 4 weeks except in leap years.

When does a year have 53 weeks?

When it starts on a Thursday, or on a Wednesday in a leap year. Then there are 53 Thursdays, and each ISO week is counted by its Thursday.

Source: ISO 8601 week dates · Updated: November 2026 · How the calendars are made

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