PHP calculate person's current age

Question

I have birth dates on my site in format 12.01.1980.

$person_date (string) = Day.Month.Year

Want to add an oldness of the perso

Answer 1

I've further extended @Jonathan's answer, to give a more 'human-friendly' response.

Using these dates:

$birthday= new DateTime('2011-11-21');
//Your date of birth.

And calling this function:

function calculate_age($birthday)
{
    $today = new DateTime();
    $diff = $today->diff(new DateTime($birthday));

    if ($diff->y)
    {
        return 'Age: ' . $diff->y . ' years, ' . $diff->m . ' months';
    }
    elseif ($diff->m)
    {
        return 'Age: ' . $diff->m . ' months, ' . $diff->d . ' days';
    }
    else
    {
        return 'Age: ' . $diff->d . ' days old!';
    }
}; 

Is returning:

Age: 1 years, 2 months

Cute - for really young ones only a few days old!

Answer 2

You can use the DateTime class and its diff() method.

<?php
$bday = new DateTime('12.12.1980');
// $today = new DateTime('00:00:00'); - use this for the current date
$today = new DateTime('2010-08-01 00:00:00'); // for testing purposes

$diff = $today->diff($bday);

printf('%d years, %d month, %d days', $diff->y, $diff->m, $diff->d);

prints 29 years, 7 month, 20 days

Answer 3

An extension of @VolkerK's answer - which is excellent! I never like seeing the age of zero, which happens if you only use the year. This function shows their age in months (if they are one month old or more), and otherwise in days.

function calculate_age($birthday)
{
    $today = new DateTime();
    $diff = $today->diff(new DateTime($birthday));

    if ($diff->y)
    {
        return $diff->y . ' years';
    }
    elseif ($diff->m)
    {
        return $diff->m . ' months';
    }
    else
    {
        return $diff->d . ' days';
    }
}