In the Gregorian calendar, a normal year consists of 365 days. Because the actual length of a sidereal year (the time required for the Earth to revolve once about the Sun) is actually 365.25635 days, a "leap year" of 366 days is used once every four years to eliminate the error caused by three normal (but short) years. Any year that is evenly divisible by 4 is a leap year: for example, 1988, 1992, and 1996 are leap years.
However, there is still a small error that must be accounted for. To eliminate this error, the Gregorian calendar stipulates that a year that is evenly divisible by 100 (for example, 1900) is a leap year only if it is also evenly divisible by 400.
For this reason, the following years are not leap years:
The following years are leap years:
Because versions of Microsoft Excel earlier than Excel 97 handle only years from 1900 to 2078, only the year 1900 is subject to the 100/400 exclusion rule of leap years in Microsoft Excel. However, in order to be compatible with other programs, Microsoft Excel treats the year 1900 as a leap year.
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
How to determine whether a year is a leap yearTo determine whether a year is a leap year, follow these steps:
- If the year is evenly divisible by 4, go to step 2. Otherwise, go to step 5.
- If the year is evenly divisible by 100, go to step 3. Otherwise, go to step 4.
- If the year is evenly divisible by 400, go to step 4. Otherwise, go to step 5.
- The year is a leap year (it has 366 days).
- The year is not a leap year (it has 365 days).
Formula to determine whether a year is a leap yearUse the following formula to determine whether the year number that is entered into a cell (in this example, cell A1) is a leap year:
If the value in cell A1 is this The formula returns
1992 Leap Year
2000 Leap Year
1900 NOT a Leap Year