PHP calculate age

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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);
36 Answers

Write a PHP script to calculate the current age of a person.

Sample date of birth : 11.4.1987

Sample Solution:

PHP Code:

<?php
$bday = new DateTime('11.4.1987'); // Your date of birth
$today = new Datetime(date('m.d.y'));
$diff = $today->diff($bday);
printf(' Your age : %d years, %d month, %d days', $diff->y, $diff->m, $diff->d);
printf("\n");
?>

Sample Output:

Your age : 30 years, 3 month, 0 days

Figured I'd throw this on here since this seems to be most popular form of this question.

I ran a 100 year comparison on 3 of the most popular types of age funcs i could find for PHP and posted my results (as well as the functions) to my blog.

As you can see there, all 3 funcs preform well with just a slight difference on the 2nd function. My suggestion based on my results is to use the 3rd function unless you want to do something specific on a person's birthday, in which case the 1st function provides a simple way to do exactly that.

Found small issue with test, and another issue with 2nd method! Update coming to blog soon! For now, I'd take note, 2nd method is still most popular one I find online, and yet still the one I'm finding the most inaccuracies with!

My suggestions after my 100 year review:

If you want something more elongated so that you can include occasions like birthdays and such:

function getAge($date) { // Y-m-d format
    $now = explode("-", date('Y-m-d'));
    $dob = explode("-", $date);
    $dif = $now[0] - $dob[0];
    if ($dob[1] > $now[1]) { // birthday month has not hit this year
        $dif -= 1;
    }
    elseif ($dob[1] == $now[1]) { // birthday month is this month, check day
        if ($dob[2] > $now[2]) {
            $dif -= 1;
        }
        elseif ($dob[2] == $now[2]) { // Happy Birthday!
            $dif = $dif." Happy Birthday!";
        };
    };
    return $dif;
}

getAge('1980-02-29');

But if you just simply want to know the age and nothing more, then:

function getAge($date) { // Y-m-d format
    return intval(substr(date('Ymd') - date('Ymd', strtotime($date)), 0, -4));
}

getAge('1980-02-29');

See BLOG


A key note about the strtotime method:

Note:

Dates in the m/d/y or d-m-y formats are disambiguated by looking at the 
separator between the various components: if the separator is a slash (/), 
then the American m/d/y is assumed; whereas if the separator is a dash (-) 
or a dot (.), then the European d-m-y format is assumed. If, however, the 
year is given in a two digit format and the separator is a dash (-, the date 
string is parsed as y-m-d.

To avoid potential ambiguity, it's best to use ISO 8601 (YYYY-MM-DD) dates or 
DateTime::createFromFormat() when possible.

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;

}

Here is the process that is more simple and works both for the formats dd/mm/yyyy and dd-mm-yyyy. This is working great for me:

    <?php
        
       $birthday = '26/04/1994';
                                                            
       $dob = strtotime(str_replace("/", "-", $birthday));
       $tdate = time();
       echo date('Y', $tdate) - date('Y', $dob);

   ?>
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