Login or Sign Up to become a member!

Less Than Dot is a community of passionate IT professionals and enthusiasts dedicated to sharing technical knowledge, experience, and assistance. Inside you will find reference materials, interesting technical discussions, and expert tips and commentary. Once you register for an account you will have immediate access to the forums and all past articles and commentaries.

From Wiki

Summary: Calculate a person's age from their date of birth

Need help with ASP.NET? Come and ask a question in our ASP.NET Forum

Here's a simple method of calculating a person's age based on their date of birth:

Output:

This Hack is part of the ASP.NET Hacks collection

Oh dear - the above example doesn't work! Dividing by 365.25 gives an approximation to someone's age, but that doesn't really cut the mustard with me.

For example: If your date of birth is 01 Jan 2001 and today is 01 Jan 2002, then 365 days have passed. 365 / 365.25 = 0.99932, Math.Floor rounds down, so we say you're zero years old when you're actually one.

Except when a multiple of four leap years have passed, you get rounding errors on your birthday: the one day you really want your age to be reported correctly. :-)

Working it out the long way round seems a bit more of a pain in the ass, but not only does it perform only integer comparisons (and thus avoids slow floating point division), but also gives the right answer: