- date: documentation ( source)
- strtotime: documentation ( source)
<?php
$Date = '24-09-2014';
$datetime1 = new DateTime(date('d-m-Y'));
$datetime2 = new DateTime(date('d-m-Y', strtotime($Date. ' + 12 days')));
$interval = $datetime1->diff($datetime2);
echo $interval->d;