Leap year

Leap years are years which contain 366 days, compared with common years which have 365 days.

The extra day in a leap year is February 29.

Years divisible by 4 are normally leap years, with some exceptions.

All of the years divisible by 4, between 1904 and 2096 inclusive, were or will be leap years.

1900 was not a leap year.

2100, 2200 and 2300 will not be leap years.

The rules for determining leap years are:

• If the year is divisible by 4, it will normally be a leap year. For example, 2016, 2020 and 2024.
• If it is divisible by 100, it will NOT normally be a leap year. For example, 2100 and 2200.
• Exceptions to the exception are years divisible by 400. Years divisible by 400 ARE leap years. For this reason, 2000 was a leap year, and 2400 will be one too.

The reason for the rules is to approximate the true number of astronomical days in a year, which is 365.24.

See also

• ACT/ACT
• Day count conventions
• Effective annual rate
• Money market