How Many Days Are in a Year? (365, 366, and Leap Years)

A common year has 365 days and a leap year has 366. The extra day, February 29, is added almost every four years to keep the calendar lined up with the seasonal (tropical) year, which is about 365.2422 days. Without that correction the seasons would slowly drift against the calendar.

Why isn't a year exactly 365 days?

The year the calendar tracks, the time from one spring equinox to the next, is about 365.2422 days, a bit less than 365 and a quarter. If every year were 365 days, the calendar would fall behind the seasons by almost a day every four years. Adding one day every fourth year corrects most of the gap, and the century rule below trims the small amount left over.

The leap-year rule

A year is a leap year when:

• it is divisible by 4, and
• if it is a century year (divisible by 100), it must also be divisible by 400.

That second clause is why 2000 was a leap year but 1900 and 2100 are not. Over 400 years this gives an average of 365.2425 days, very close to that seasonal-year figure.

How many days are in each month?

Seven months have 31 days (January, March, May, July, August, October, December), four have 30 (April, June, September, November), and February has 28, or 29 in a leap year. The old rhyme “thirty days has September” still works. For the full breakdown by layout, see our guide to printable calendar types.

How many working days are in a year?

After removing weekends, a 365-day year has about 260 working days. Public holidays and paid leave bring the practical figure most people plan around down to roughly 230 to 250. The exact number depends on your country, which you can check on the public holidays calendar. For the weeks view of the same question, see how many weeks are in a year.

Frequently asked questions

How many days are in a leap year?
366. The extra day is February 29, which occurs in years divisible by 4, with the century exception.

Which years are leap years?
Years divisible by 4, except century years that are not divisible by 400. Examples: 2016, 2020, 2024, 2028, 2032.

How many days are in a year on average?
Over the 400-year Gregorian cycle the average is 365.2425 days, which is why the leap-year rules exist.

What day of the year is it today?
Add the day of the month to the first-of-month value from a day-of-year table, then subtract one. Our Julian date calendar guide has the full table, and you can see any full year laid out in the calendar generator.

Leap-year rules follow the Gregorian calendar, and NASA explains why we have leap years. The mean tropical year is about 365.2422 days.