Leap Year Calculator — is it a leap year?

How it works

A common year has 365 days, but a solar year is about 365.2422 days — nearly a quarter-day longer. To keep the calendar aligned with the seasons, an extra day (February 29) is added in leap years. The Gregorian rule, as stated by the US Naval Observatory, is:

• If a year is divisible by 4, it is a leap year,
• except century years (divisible by 100), which are leap years only if divisible by 400.

That exception exists because adding a full day every four years slightly overcorrects. Skipping three leap days every 400 years (at 1700, 1800, 1900, but not 2000) brings the average calendar year to 365.2425 days — very close to the true solar year.

A leap year has 366 days and a 29-day February; a common year has 365 days and a 28-day February. The calculator also shows how many years remain until the next leap year, accounting for the skipped centuries.

Worked example

Take 2026. It is not divisible by 4 (2026 ÷ 4 leaves a remainder of 2), so it is a Common year — 365 days, with 28 days in February. The next leap year is 2028, two years away. By contrast 2024 is divisible by 4 and not a century, so it is a leap year; 1900 is divisible by 100 but not 400, so it is common; and 2000 is divisible by 400, so it is a leap year.

Frequently asked questions

How do you know if a year is a leap year?

Check divisibility: if the year divides evenly by 4 it is a leap year, unless it is a century year (divisible by 100), which must also divide by 400. So 2024 is a leap year, but 1900 is not because it is not divisible by 400.

Why isn't every fourth year a leap year?

Adding a day every four years slightly overcorrects, because the solar year is about 365.2422 days, not 365.25. Dropping three leap days every 400 years — the skipped centuries — keeps the calendar accurate to within a day for thousands of years.

Was 2000 a leap year?

Yes. Although 2000 is a century year, it is divisible by 400, so it kept its leap day. This is the exception to the exception, and it is why 2000 had a February 29 while 1900 and 2100 do not.

How many days are in a leap year?

A leap year has 366 days — one more than a common year's 365 — because February has 29 days instead of 28. The extra day keeps the calendar synchronized with Earth's orbit.

Which upcoming years are leap years?

Leap years fall every four years: 2024, 2028, 2032, 2036 and so on. The pattern only breaks at century years not divisible by 400 — the next such skip is 2100.

Why does February have the extra day?

By historical convention from the Roman calendar, the adjustment day was placed in February, the shortest month. So the leap day became February 29, present only in leap years.