What is a leap year?

A leap year is a calendar year that contains an additional day—February 29th—making it 366 days long instead of the usual 365. This extra day compensates for the fact that Earth's orbit around the Sun takes approximately 365.25 days, not exactly 365. Without leap years, our calendar would gradually drift out of sync with the seasons by about 24 days every century.

How are leap years calculated?

The Gregorian calendar, used by most of the world today, follows specific rules to determine leap years:

  1. Divisible by 4: A year must be divisible by 4 to be a leap year
  2. Century exception: Years divisible by 100 are NOT leap years
  3. 400-year exception: Unless the year is also divisible by 400, then it IS a leap year

For example, 2000 was a leap year (divisible by 400), but 1900 was not (divisible by 100 but not 400). The year 2024 is a leap year (divisible by 4, not a century year).

Why do we need leap years?

Earth completes one orbit around the Sun in approximately 365.2422 days. If we used a simple 365-day calendar without corrections, the calendar would shift by about one day every four years. After a century, summer would begin in what we call "August" and winter in "February." Leap years keep our calendar aligned with Earth's position in its orbit, ensuring seasons occur at consistent times each year.

Tool description

This leap year calculator instantly determines whether any year is a leap year and shows you the nearest leap years before and after your selected date. It calculates the exact number of years between your input and the adjacent leap years, making it easy to plan for events or understand calendar patterns.

Examples

Input Year Is Leap Year Previous Leap Next Leap Years Since Years Until
2025 No 2024 2028 1 3
2024 Yes 2020 2028 4 4
2100 No 2096 2104 4 4
2000 Yes 1996 2004 4 4
1900 No 1896 1904 4 4

Features

  • Instant leap year detection: Immediately shows whether any year is a leap year using the Gregorian calendar rules
  • Adjacent leap year finder: Displays both the previous and next leap years relative to your input
  • Year distance calculation: Shows exactly how many years separate your input from nearby leap years
  • Quick navigation buttons: Jump directly to the previous or next leap year with one click
  • Works with any year: Supports historical dates and far-future years alike

Use cases

  • Event planning: Determine when the next February 29th occurs for birthday celebrations or leap day events
  • Academic research: Verify leap year calculations for historical or astronomical studies
  • Software development: Test date logic and validate leap year algorithms in applications
  • Financial calculations: Account for the extra day in leap years when computing interest or time-based metrics
  • Trivia and education: Quickly answer questions about specific years being leap years