Leap year calculator
Find out if a year is a leap year, how many days it has and the next leap year.
A year is leap if divisible by 4 — except centuries not divisible by 400. So 2000 was a leap year, but 1900 was not.
How the calculation works
The Gregorian rule: a leap year is divisible by 4, but not by 100, unless also divisible by 400. The extra day (Feb 29) corrects the gap between the civil year (365 days) and the solar year (~365.2422 days).
Examples
- 2024 → divisible by 4, not 100 → leap year (has Feb 29).
- 2100 → divisible by 100, not 400 → NOT a leap year.
Frequently asked questions
Why was 2000 a leap year but not 1900?
Both are divisible by 100, but only 2000 is divisible by 400 — the exception to the exception.
How many days in a leap year?
366 — one more than the usual 365, thanks to Feb 29.
When do Feb 29 people celebrate?
In non-leap years, usually Feb 28 or Mar 1.
Was 1900 a leap year?
No. It is divisible by 4 and by 100 but not by 400, so it falls under the exception. 2000 was a leap year; the next exception is 2100.
Why does the rule have exceptions?
Because the solar year is about 365.2422 days. Adding a day every four years overshoots slightly; the century exceptions correct it to an average of 365.2425 days.
When do 29 February babies celebrate?
On 28 February or 1 March in common years, depending on the country. In software it is a classic source of bugs.
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Updated on June 30, 2026 · by Rafael Rossi · Methodology & sources