Check if any year is a leap year, explore next and past leap years, and understand the Gregorian 400-year rule.
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A leap year calculator determines whether a given calendar year contains 366 days instead of 365, with February 29 as the leap day. It implements the complete three-part Gregorian rule designed to keep our calendar synchronized with Earth’s astronomical orbit around the Sun.
\text{LeapYear}(Y) = (Y \equiv 0 \pmod 4 \land Y \not\equiv 0 \pmod{100}) \lor (Y \equiv 0 \pmod{400})A year is a leap year if divisible by 4, unless it is divisible by 100, unless it is also divisible by 400.
Scenario: Why was the year 2000 a leap year, but 2100 will NOT be a leap year?
Year 2000 is divisible by 100, but ALSO divisible by 400 (2000 / 400 = 5) -> Leap Year!
Year 2100 is divisible by 4 and 100, but NOT divisible by 400 (2100 / 400 = 5.25) -> Common Year (365 days).
1. The year must be divisible by 4. 2. If divisible by 100, it is NOT a leap year, UNLESS: 3. It is also divisible by 400.
1900 is divisible by 4 and 100, but not divisible by 400 (1900 ÷ 400 = 4.75), so it was a common year with 365 days.
Following 2024, the next leap years are 2028, 2032, 2036, 2040, and 2044.
February has 29 days in a leap year, compared to 28 days in a common year.
Add or subtract days, weeks, months, and years from any date or calculate the exact duration between two dates.
Find out what day of the week any past or future date falls on, with day-of-year numbers and historical facts.
Calculate exact age in years, months, and days, countdown to next birthday, generation name, and total days lived.
2026 is NOT a leap year because it is not evenly divisible by 4.
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