PHP calculate age

Question

I'm looking for a way to calculate the age of a person, given their DOB in the format dd/mm/yyyy.

I was using the following function which worked fine for several months until some kind of glitch caused the while loop to never end and grind the entire site to a halt. Since there are almost 100,000 DOBs going through this function several times a day, it's hard to pin down what was causing this.

Does anyone have a more reliable way of calculating the age?

//replace / with - so strtotime works
$dob = strtotime(str_replace("/","-",$birthdayDate));       
$tdate = time();

$age = 0;
while( $tdate > $dob = strtotime('+1 year', $dob))
{
    ++$age;
}
return $age;

EDIT: this function seems to work OK some of the time, but returns "40" for a DOB of 14/09/1986

return floor((time() - strtotime($birthdayDate))/31556926);

Answer 1

If you want to caculate the Age of using the dob, you can also use this function. It uses the DateTime object.

function calcutateAge($dob){

        $dob = date("Y-m-d",strtotime($dob));

        $dobObject = new DateTime($dob);
        $nowObject = new DateTime();

        $diff = $dobObject->diff($nowObject);

        return $diff->y;

}

Answer 2

How about launching this query and having MySQL calculating it for you:

SELECT 
username
,date_of_birth
,(PERIOD_DIFF( DATE_FORMAT(CURDATE(), '%Y%m') , DATE_FORMAT(date_of_birth, '%Y%m') )) DIV 12 AS years
,(PERIOD_DIFF( DATE_FORMAT(CURDATE(), '%Y%m') , DATE_FORMAT(date_of_birth, '%Y%m') )) MOD 12 AS months
FROM users

Result:

r2d2, 1986-12-23 00:00:00, 27 , 6 

The user has 27 years and 6 months (it counts an entire month)

Answer 3

Following the first logic, you have to use = in the comparison.

<?php 
    function age($birthdate) {
        $birthdate = strtotime($birthdate);
        $now = time();
        $age = 0;
        while ($now >= ($birthdate = strtotime("+1 YEAR", $birthdate))) {
            $age++;
        }
        return $age;
    }

    // Usage:

    echo age(implode("-",array_reverse(explode("/",'14/09/1986')))); // format yyyy-mm-dd is safe!
    echo age("-10 YEARS") // without = in the comparison, will returns 9.

?>

Answer 4

$birthday_timestamp = strtotime('1988-12-10');  

// Calculates age correctly
// Just need birthday in timestamp
$age = date('md', $birthday_timestamp) > date('md') ? date('Y') - date('Y', $birthday_timestamp) - 1 : date('Y') - date('Y', $birthday_timestamp);

Answer 5

//replace / with - so strtotime works
$dob = strtotime(str_replace("/","-",$birthdayDate));       
$tdate = time();
return date('Y', $tdate) - date('Y', $dob);

Answer 6

The top answer for this is OK but only calualtes the year a person was born, I tweaked it for my own purposes to work out the day and month. But thought it was worth sharing.

This works by taken a timestamp of the the users DOB, but feel free to change that

$birthDate = date('d-m-Y',$usersDOBtimestamp);
$currentDate = date('d-m-Y', time());
//explode the date to get month, day and year
$birthDate = explode("-", $birthDate);
$currentDate = explode("-", $currentDate);
$birthDate[0] = ltrim($birthDate[0],'0');
$currentDate[0] = ltrim($currentDate[0],'0');
//that gets a rough age
$age = $currentDate[2] - $birthDate[2];
//check if month has passed
if($birthDate[1] > $currentDate[1]){
      //user birthday has not passed
      $age = $age - 1;
} else if($birthDate[1] == $currentDate[1]){ 
      //check if birthday is in current month
      if($birthDate[0] > $currentDate[0]){
            $age - 1;
      }


}
   echo $age;