📅 Leap Year Calculator

Check if a year is a leap year and find next leap years. February 29 calculator with historical data.

Calculator
Timeline
Rules
History
FAQ

Leap Year Calculator

Enter a year to check if it's a leap year. Leap years have 366 days with February 29th.

Leap Year Timeline

Upcoming and recent leap years with key information.

Recent and Upcoming Leap Years

2020
Recent Leap Year
366 days, February 29 was a Saturday. Olympic year.
2024
Last Leap Year
366 days, February 29 was a Thursday. Olympic year.
2025
Current Year (Not Leap)
365 days, February has 28 days only.
2028
Next Leap Year
366 days, February 29 will be a Tuesday. Olympic year.
2032
Future Leap Year
366 days, February 29 will be a Sunday. Olympic year.

21st Century Leap Years

YearFeb 29 DayOlympic YearNotable Events
2000TuesdayYesMillennium leap year, Y2K
2004SundayYesAthens Olympics, Facebook launch
2008FridayYesBeijing Olympics, Financial crisis
2012WednesdayYesLondon Olympics, Mayan calendar end
2016MondayYesRio Olympics, Brexit vote
2020SaturdayYesTokyo Olympics (delayed), COVID-19
2024ThursdayYesParis Olympics
2028TuesdayYesLos Angeles Olympics

Leap Year Rules

Understanding the mathematical rules that determine leap years.

Leap Year Calculation Rules

1
If the year is divisible by 4, it's a leap year candidate
2
If the year is divisible by 100, it's NOT a leap year (exception)
3
If the year is divisible by 400, it IS a leap year (exception to exception)
Examples:
  • 2024: Divisible by 4 → Leap Year ✅
  • 2025: Not divisible by 4 → Not Leap Year ❌
  • 1900: Divisible by 4 and 100, but not 400 → Not Leap Year ❌
  • 2000: Divisible by 4, 100, and 400 → Leap Year ✅
1600
Leap Year
1700
Not Leap
1800
Not Leap
1900
Not Leap
2000
Leap Year
2100
Not Leap
2200
Not Leap
2300
Not Leap
2400
Leap Year
Why Do We Have Leap Years?
Earth's orbit around the Sun takes approximately 365.25 days. To keep our calendar synchronized with Earth's orbit, we add an extra day every 4 years. The complex rules account for the fact that it's actually 365.2422 days, not exactly 365.25.

Leap Year History

Historical development of leap year systems and calendar reforms.

Calendar System Evolution

YearCalendar SystemLeap Year RuleCreator/Reformer
46 BCJulian CalendarEvery 4 yearsJulius Caesar
1582Gregorian CalendarCurrent rules (4, 100, 400)Pope Gregory XIII
1752British adoptionGregorian rulesBritish Parliament
1918Soviet adoptionGregorian rulesSoviet Government
1949Chinese adoptionGregorian rulesPeople's Republic of China

Notable Leap Year Events

46 BC
Julian Calendar Introduced
Julius Caesar introduces leap years every 4 years. Year had 445 days!
1582
Gregorian Calendar Reform
Pope Gregory XIII refines leap year rules. 10 days skipped in October.
1896
First Modern Olympics
Olympics begin tradition of occurring in leap years.
1904
Leap Day Traditions
Sadie Hawkins traditions and leap day proposals become popular.
2000
Y2K Leap Year
First century leap year in 400 years tests computer systems.
Interesting Leap Year Facts:
  • Leap Day Babies: About 4 million people worldwide are born on February 29
  • Olympics: Summer Olympics have been held in leap years since 1896 (except wartime)
  • Elections: US Presidential elections occur in leap years
  • Traditions: In some cultures, women can propose to men on leap day
  • Programming: Leap years often cause bugs in software systems

Frequently Asked Questions

  • Why do leap years exist? Earth's orbit takes about 365.25 days, not exactly 365. Leap years keep our calendar aligned with Earth's position relative to the Sun.
  • Why isn't it exactly every 4 years? Earth's orbit is actually 365.2422 days, not 365.25. The century rules (100/400) account for this difference.
  • What happens to people born on February 29? "Leaplings" typically celebrate on February 28 or March 1 in non-leap years. Legally, they age on February 28.
  • Are there any countries that don't use leap years? Most countries use the Gregorian calendar. Some traditional calendars (like Islamic) don't use leap years but have different adjustment methods.
  • What's special about century years? Century years (1700, 1800, 1900, 2100) are not leap years unless divisible by 400. This keeps the calendar accurate.
  • Will leap years ever stop? No, but the rules might need adjustment in thousands of years as Earth's rotation gradually slows down.
  • How many leap years are there per century? Usually 24 leap years per century (except centuries like 1700-1799 which have 23).
  • What was the longest year in history? 46 BC had 445 days when Julius Caesar introduced the Julian calendar and had to catch up with seasonal drift.