Leap Year Checker
Check whether any year is a leap year.
The leap year rule
A year is a leap year if it's divisible by 4 — except years divisible by 100, unless they're also divisible by 400. That's why 2000 was a leap year but 1900 and 2100 are not.
Where leap years actually cause problems
February 29 is a common source of real bugs: payroll and billing systems that assume a fixed 28-day February, birthday and anniversary reminders for the roughly 1-in-1,461 people actually born on a leap day, and subscription or contract terms written as "365 days" that quietly fall a day short in a leap year. Checking a year here before you hard-code a date range is faster than debugging it after the fact.
Frequently asked questions
What is the exact rule for leap years?
Divisible by 4 → leap year, unless also divisible by 100 → not a leap year, unless also divisible by 400 → leap year after all. 2024 and 2028 qualify; 1900 and 2100 do not, despite being divisible by 4.
Why isn't every 4th year automatically a leap year?
Because a year is about 365.2422 days, not exactly 365.25 — the century exception (divisible by 100 but not 400) corrects for that small overcount roughly every 400 years.
When is the next leap year?
Enter any year to check it instantly, or check consecutive years to find the nearest one before or after.