How to use this reference
A Gregorian leap year contains February 29 and has 366 days. Most years divisible by four are leap years, but century years are exceptions unless also divisible by 400. For example, 1900 was not a leap year and 2000 was. The extra rule keeps the calendar closer to the seasonal year.
Enter a year to see the divisibility reasoning and the nearest leap years strictly before and after it. The calculator applies Gregorian rules consistently across its supported year range; historical countries adopted this calendar at different times, so a historical document may instead use another calendar system.
Leap-day rules matter when adding months or interpreting birthdays. Use the Months Until/Since Calculator for clamped month arithmetic, the Age Calculator for an age calculation, or the ISO Week Number Calculator for calendar-week reporting.
Frequently asked questions
Why was 1900 not a leap year?
It is divisible by 100 but not by 400, so it fails the Gregorian century exception.
Why was 2000 a leap year?
It is divisible by 400, which restores leap-year status even though it is a century year.
Does the previous or next leap year include the entered year?
No. These results refer strictly to a year before or after the entered year.