PHP calculate age

<?php

//date in mm/dd/yyyy format; or it can be in other formats as well

$birthDate = "2/15/1988";

//explode the date to get month, day and year

$birthDate = explode("/", $birthDate);

//get age from date or birthdate

$age = (date("md", date("U", mktime(0, 0, 0, $birthDate[0], $birthDate[1], $birthDate[2]))) > date("md")

? ((date("Y") - $birthDate[2]) - 1)

: (date("Y") - $birthDate[2]));

echo "Age is:" . $age;