How the Leap Year Calculator Works
Determining whether a year is a leap year is mathematically more complex than simply dividing by four. Our calculator instantly applies the exact Gregorian calendar rules to any year you enter, telling you immediately if February will have 28 or 29 days.
Why do we need Leap Years?
The Earth takes approximately 365.2422 days to complete one orbit around the Sun. Because our standard calendar has exactly 365 days, we would lose almost six hours every year if we didn't correct it. By adding an extra day roughly every four years, we keep our seasons from slowly drifting out of sync with the calendar.
Frequently Asked Questions
A leap year is a year that contains an additional day (February 29th) to keep the calendar year synchronized with the astronomical year.
Generally, leap years occur every four years. However, there are exceptions for century years to keep the math precise.
A year is a leap year if it is divisible by 4. But, if it is divisible by 100, it is NOT a leap year, unless it is also divisible by 400.
A normal year has 365 days, but a leap year has exactly 366 days.