Leap Year Calculator
Enter a year to check whether it is a leap year and see the next leap year after it.
The Gregorian rule is simple: divisible by 4, except century years must also be divisible by 400.
Leap Year Result
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Days in year: --
Next leap year: --
Run the calculation to see the Gregorian rule in action.
Quick Answer
Leap years have 366 days. A year is a leap year when it is divisible by 4, except century years must also be divisible by 400.
How to Calculate a Leap Year
- Check whether the year is divisible by 4.
- If it is a century year, also check divisibility by 400.
- If both rules pass, the year is a leap year.
Formula
Leap year = divisible by 4 AND (not divisible by 100 OR divisible by 400)
Days in a leap year = 366
Worked Examples
Example 1: 2024 is a leap year because it is divisible by 4 and not a century year.
Example 2: 1900 is not a leap year because it is divisible by 100 but not by 400.
Example 3: 2000 is a leap year because it is divisible by 400.
How to Interpret Your Results
| Output | Meaning | Action |
|---|---|---|
| Leap year | The year has 366 days. | Use February 29 when counting dates. |
| Common year | The year has 365 days. | Use the standard February length. |
| Century exception | The year ends in 00, so the 400-year rule applies. | Check the 400-divisibility rule carefully. |
Frequently Asked Questions
They keep the calendar aligned with the Earth's orbit around the Sun, which is slightly longer than 365 days.
Not always. Century years need the extra divisibility by 400, which is why 1900 is not a leap year and 2000 is.
The next leap year after 2026 is 2028, because leap years repeat every four years unless a century rule changes the pattern.
Related Calculators
References
- OmniCalculator reference page
- The Gregorian leap-year rule is the standard used in modern calendars.
- Last reviewed: March 2026.