- date: documentation ( source)
- strtotime: documentation ( source)
<?php
$date = strtotime("2014-09-16");
echo strtotime('+15 weeks',$date);
$timestamp = strtotime('+15 weeks',$date);
echo " Date=".date('Y-m-d', $timestamp);
echo " Date=".date('Y-W-d', $timestamp);