/*
 * Here are several ways to do this, depending on how much accuracy/info you want.
 */

//Ex: 5.3482484954333
$age = floor(time() - strtotime('2009-11-09')) / 31556926;

//Ex: You are 05 Years, 04 Months, 7 Days Old
$interval = date_diff(date_create(), date_create('2009-11-09'));
echo $interval->format("You are %Y Years, %M Months, %d Days Old");

//Ex: You are %Y Years, %M Months, %d Days, %H Hours, %i Minutes, %s Seconds Old		
$interval = date_diff(date_create(), date_create('2009-11-09 00:00:00'));
echo $interval->format("You are %Y Years, %M Months, %d Days, %H Hours, %i Minutes, %s Seconds Old");	


//Ex: findage("21-04-1969"); == Age is $years years $months months.
//date_default_timezone_set('Europe/Moscow');
ini_set("date.timezone", "Europe/Moscow");//I prefer this over above
Exfunction findage($dob)
{
    $localtime = getdate();
    $today = $localtime['mday']."-".$localtime['mon']."-".$localtime['year'];
    $dob_a = explode("-", $dob);
    $today_a = explode("-", $today);
    $dob_d = $dob_a[0];$dob_m = $dob_a[1];$dob_y = $dob_a[2];
    $today_d = $today_a[0];$today_m = $today_a[1];$today_y = $today_a[2];
    $years = $today_y - $dob_y;
    $months = $today_m - $dob_m;
    if ($today_m.$today_d < $dob_m.$dob_d) 
    {
        $years--;
        $months = 12 + $today_m - $dob_m;
    }

    if ($today_d < $dob_d) 
    {
        $months--;
    }

    $firstMonths=array(1,3,5,7,8,10,12);
    $secondMonths=array(4,6,9,11);
    $thirdMonths=array(2);

    if($today_m - $dob_m == 1) 
    {
        if(in_array($dob_m, $firstMonths)) 
        {
            array_push($firstMonths, 0);
        }
        elseif(in_array($dob_m, $secondMonths)) 
        {
            array_push($secondMonths, 0);
        }elseif(in_array($dob_m, $thirdMonths)) 
        {
            array_push($thirdMonths, 0);
        }
    }
    echo "<br><br> Age is $years years $months months.";
}