<?php
// date_default_timezone_set('Europe/Berlin'); // you are required to set a timezone
$date1 = new \DateTime('2009-08-12');
$date2 = new \DateTime('2003-04-14');
$diff = $date1->diff($date2);
echo (($diff->format('%y') * 12) + $diff->format('%m')) . " full months difference";