Check whether any given year is a leap year in the Gregorian calendar.
How It Works
How Leap Year Calculator Works
A year is a leap year if it divides evenly by 4 — unless it also divides evenly by 100, in which case it isn't a leap year after all, unless it divides evenly by 400, in which case it is one again. That extra layer of exceptions is what keeps the calendar accurately synced with Earth's actual orbit over long stretches of time.
Worked Example
See It In Action
The year 1900 divides evenly by 4 and by 100 but not by 400, so it was not a leap year — while 2000 divides evenly by 400 too, so it was one.
FAQ
Frequently Asked Questions
Why does the calendar need leap years at all?
Earth's orbit around the sun takes about 365.2422 days, not an even 365 — adding an extra day roughly every 4 years keeps the calendar from slowly drifting out of sync with the actual seasons.
Why the extra exception for century years?
A leap year every 4 years alone slightly overcorrects, since 365.25 is a bit more than the true value — skipping the leap day in three out of every four century years (like 1900, but not 2000) fine-tunes the average length much closer to the real solar year.
