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

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.

Answer 2

Try any of these using DateTime object

$hours_in_day   = 24;
$minutes_in_hour= 60;
$seconds_in_mins= 60;

$birth_date     = new DateTime("1988-07-31T00:00:00");
$current_date   = new DateTime();

$diff           = $birth_date->diff($current_date);

echo $years     = $diff->y . " years " . $diff->m . " months " . $diff->d . " day(s)"; echo "<br/>";
echo $months    = ($diff->y * 12) + $diff->m . " months " . $diff->d . " day(s)"; echo "<br/>";
echo $weeks     = floor($diff->days/7) . " weeks " . $diff->d%7 . " day(s)"; echo "<br/>";
echo $days      = $diff->days . " days"; echo "<br/>";
echo $hours     = $diff->h + ($diff->days * $hours_in_day) . " hours"; echo "<br/>";
echo $mins      = $diff->h + ($diff->days * $hours_in_day * $minutes_in_hour) . " minutest"; echo "<br/>";
echo $seconds   = $diff->h + ($diff->days * $hours_in_day * $minutes_in_hour * $seconds_in_mins) . " seconds"; echo "<br/>";

Reference http://www.calculator.net/age-calculator.html

Answer 3

I find this works and is simple.

Subtract from 1970 because strtotime calculates time from 1970-01-01 (http://php.net/manual/en/function.strtotime.php)

function getAge($date) {
    return intval(date('Y', time() - strtotime($date))) - 1970;
}

Results:

Current Time: 2015-10-22 10:04:23

getAge('2005-10-22') // => 10
getAge('1997-10-22 10:06:52') // one 1s before  => 17
getAge('1997-10-22 10:06:50') // one 1s after => 18
getAge('1985-02-04') // => 30
getAge('1920-02-29') // => 95

Answer 4

$tz  = new DateTimeZone('Europe/Brussels');
$age = DateTime::createFromFormat('d/m/Y', '12/02/1973', $tz)
     ->diff(new DateTime('now', $tz))
     ->y;

As of PHP 5.3.0 you can use the handy DateTime::createFromFormat to ensure that your date does not get mistaken for m/d/Y format and the DateInterval class (via DateTime::diff) to get the number of years between now and the target date.

Answer 5

If you can't seem to use some of the newer functions, here's something I whipped up. Probably more than you need, and I'm sure there are better ways, but it's easy to read, so it should do the job:

function get_age($date, $units='years')
{
    $modifier = date('n') - date('n', strtotime($date)) ? 1 : (date('j') - date('j', strtotime($date)) ? 1 : 0);
    $seconds = (time()-strtotime($date));
    $years = (date('Y')-date('Y', strtotime($date))-$modifier);
    switch($units)
    {
        case 'seconds':
            return $seconds;
        case 'minutes':
            return round($seconds/60);
        case 'hours':
            return round($seconds/60/60);
        case 'days':
            return round($seconds/60/60/24);
        case 'months':
            return ($years*12+date('n'));
        case 'decades':
            return ($years/10);
        case 'centuries':
            return ($years/100);
        case 'years':
        default:
            return $years;
    }
}

Example Use:

echo 'I am '.get_age('September 19th, 1984', 'days').' days old';

Hope this helps.

Answer 6

It is a problem when you use strtotime with DD/MM/YYYY. You cant use that format. Instead of it you can use MM/DD/YYYY (or many others like YYYYMMDD or YYYY-MM-DD) and it should work properly.