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Time & Date

Leap Year Checker

Check if a year is a leap year and discover the calendar patterns.

Status

366days

2024 is a leap year

Next leap year2,028
Previous leap year2,020

A leap year is divisible by 4, except for years divisible by 100 unless also divisible by 400.

What is the Leap Year Checker?

A leap year is a calendar year that contains 366 days instead of 365, with an extra day (February 29) added to keep the calendar aligned with Earth's orbit. A year is a leap year if it is divisible by 4, except for years divisible by 100 (which are not leap years) unless they are also divisible by 400 (in which case they are leap years).

How it works

The leap year checker applies the Gregorian calendar rule: it divides the year by 4, 100, and 400 in sequence. First, it checks if the year is divisible by 400—if yes, it is a leap year. If not, it checks if divisible by 100—if yes, it is not a leap year. If neither rule applies, it checks if divisible by 4—if yes, it is a leap year. Otherwise, it is a common year with 365 days.

IF (year % 400 == 0) THEN leap year; ELSE IF (year % 100 == 0) THEN not leap year; ELSE IF (year % 4 == 0) THEN leap year; ELSE not leap year

The % symbol means 'remainder after division'; year % 400 checks divisibility by 400. The cascade order prevents exceptions like 1900 (divisible by 100 but not 400, so not a leap year) from being miscalculated.

Examples

InputResultNotes
2024Leap year2024 is divisible by 4 and not by 100, so it contains 366 days.
1900Not a leap year1900 is divisible by 100 but not by 400, so despite being divisible by 4, it has only 365 days.
2000Leap year2000 is divisible by 400, making it a leap year despite centuries typically being common years.

How to use the Leap Year Checker

  1. Enter a year (e.g., 2024 or 1900) into the input field.
  2. Click the 'Check' button or press Enter.
  3. The tool instantly displays whether the year is a leap year or common year.
  4. Review the explanation of why that year meets or fails the leap year criteria.
  5. Use the result to adjust schedules, plan events, or verify historical dates.

Benefits

  • Avoid confusion about which years have February 29—saves time recalculating the 4-100-400 rule by hand.
  • Ensures accurate date handling in scheduling, project planning, and calendar applications.
  • Useful for software developers, genealogists, historians, and accountants who work with date logic.
  • Free and instant—no need to memorize or look up leap year lists.
  • Clarifies the logic so you understand why years like 1900 are exceptions despite being divisible by 4.

Tips & common mistakes

Common mistakes

  • Assuming every 4 years is a leap year (missing the 100 and 400 exceptions)—1900 and 1800 were not leap years.
  • Forgetting that century years (1700, 1800, 1900, etc.) are only leap years if divisible by 400.
  • Entering a date instead of just a year, or using letters instead of digits.
  • Not realizing that February 29 only exists in leap years, causing off-by-one errors in date ranges.

Tips

  • For any century year (ending in 00), remember the 400 rule: 2000 was a leap year, but 1900 was not.
  • If you are calculating days between two dates that cross February, check whether February 29 falls between them.
  • In code, use this tool to validate leap year logic in your own date calculations.
  • Plan birthday or anniversary events in advance if they fall on February 29—the next leap year after 2024 is 2028.

Frequently asked questions

Why does the leap year rule have three conditions?

Earth's orbit is about 365.2425 days, not 365. The 4-year rule overshoots, the 100-year rule overcorrects, and the 400-year rule balances it. Together they keep the calendar accurate for thousands of years.

Is 2000 a leap year?

Yes. 2000 is divisible by 400, so it is a leap year—the first century to be a leap year since 1600.

When is the next leap year after 2024?

2028. Leap years occur every 4 years in most cases, so 2024, 2028, 2032, and so on.

What happens if someone is born on February 29?

They are called a 'leapling.' Many celebrate their birthday on February 28 or March 1 in non-leap years.

Does any other calendar use the leap year rule?

The Gregorian calendar (used worldwide) uses it. The Julian calendar used a simpler 4-year rule, which is why dates drift over centuries.

Will there ever be a leap year in 2100?

No. 2100 is divisible by 100 but not by 400, so it will be a common year with 365 days.

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FreeTooz Editorial Team · Last reviewed July 2026

Reviewed for accuracy. Results are estimates for general information and are not professional (medical, financial or legal) advice.