Understanding the result
A year has 366 days if it is a leap year and 365 days if it is not. The result also shows the year as whole weeks plus leftover days, and a table lists the length of every month in that year.
How many days are in a year?
A common calendar year has 365 days. A leap year has 366, because February gains a 29th day. That is 52 weeks and 1 day in a common year, or 52 weeks and 2 days in a leap year.
The extra day matters for anything that counts days across a year: interest calculations, subscription periods, ages and project schedules.
How it works
The tool applies the Gregorian leap year rule: divisible by 4, except century years, except century years divisible by 400. It then sums the lengths of the twelve months, with February at 29 days in a leap year and 28 otherwise.
Examples
2024
A leap year with 366 days: 52 weeks and 2 days. February has 29 days.
2025
A common year with 365 days: 52 weeks and 1 day.
1900
365 days. It is a century year not divisible by 400, so it was not a leap year, although it is divisible by 4.
Things to keep in mind
- This is the Gregorian calendar year. Other calendars, such as the Islamic, Hebrew and Chinese calendars, have different year lengths.
- The Gregorian rule is applied to years before 1582 as well, which is the usual convention in computing and in ISO 8601.
- Financial "days in a year" conventions such as 360 or 365 are agreed methods for interest calculations and differ from the calendar length.