One of the many features of Excel is being nosy. That's right, you can quickly calculate a persons age as long as you have their birth date.

To calculate the age, the DATEDIF function, set to check year, determines the number of years between the date in the DOB cell and the current date.

If you need to count or calculate number of Leap Years between two dates in Excel or list of two dates in Excel, make use of this formula to get things done.

Since Leap Year occurs once every four years — 2020, 2024 and 2028 is the next one, for example — this "Leap Day math" applies to people born Feb. 29.