Best way to find out the age of someone

Im trying to find out how old someone is:

ive tried doing it like this:

DateDiff("yyyy",DOB,Date())

But this seems to just go off the year and nothing more which is obviously no good since a year lasts 12 months.

Anyone got any ideas what the best way is?

Google is your friend (http://www.google.co.uk/search?q=ASP+calculate+age)