Leap Year Calculator

A leap year is a calendar year that contains an additional day compared to a common year. The extra day is added to February, making it 29 days instead of 28.

Leap Year Rules

The Gregorian calendar follows specific rules to determine leap years:

• A year is a leap year if it is divisible by 4
• However, if the year is divisible by 100, it is NOT a leap year
• Exception: If the year is divisible by 400, it IS a leap year

Examples: 2000 was a leap year (divisible by 400), but 1900 was not (divisible by 100 but not 400)

Why Do We Have Leap Years?

Leap years exist to keep our calendar year synchronized with the astronomical year. The Earth takes approximately 365.25 days to orbit the Sun, so we add an extra day every four years to account for the extra quarter day.

Historical Background

The concept of leap years was introduced by Julius Caesar in 46 BC with the Julian calendar. The current Gregorian calendar, introduced by Pope Gregory XIII in 1582, refined the leap year rules to be more accurate.

Leap Year Frequency

In the Gregorian calendar, leap years occur approximately every 4 years. More precisely, there are 97 leap years in every 400-year cycle, making the average year length 365.2425 days.

Examples

Here are some examples of leap year calculations:

• 2024 is a leap year (divisible by 4)
• 2100 will not be a leap year (divisible by 100 but not 400)
• 2000 was a leap year (divisible by 400)
• 1900 was not a leap year (divisible by 100 but not 400)