About Leap Years

A leap year is a calendar year that contains an additional day (February 29) added to keep the calendar year synchronized with the astronomical year.

Leap Year Rules

A year is a leap year if it meets the following conditions:

1. The year is divisible by 4
2. If the year is divisible by 100, it is NOT a leap year, UNLESS:
3. The year is also divisible by 400, then it IS a leap year

For example:

• 2020 is a leap year (divisible by 4 but not by 100)
• 2100 is NOT a leap year (divisible by 100 but not by 400)
• 2000 is a leap year (divisible by 400)

Why Do We Need Leap Years?

Earth takes approximately 365.25 days to orbit the Sun. Without leap years, our calendar would slowly drift out of alignment with the seasons. Adding an extra day every four years (with exceptions) keeps our calendar accurately aligned with Earth's revolution around the Sun.

Interesting Leap Year Facts

• People born on February 29 (leap day) are called "leaplings" or "leap-year babies"
• Leap years have 366 days instead of the usual 365
• The odds of being born on a leap day are about 1 in 1,461
• The first leap year in the modern sense was 45 BCE
• In some traditions, women were allowed to propose marriage to men only during leap years

Calendar Systems and Leap Years

Different calendar systems handle the need for leap periods in various ways:

• Gregorian Calendar: The most widely used calendar today, uses the leap year rules described above
• Julian Calendar: A simpler system that adds a leap day every 4 years without exceptions
• Chinese Calendar: Uses leap months rather than leap days
• Hebrew Calendar: Adds a leap month seven times in a 19-year cycle