- date_diff: documentation ( source)
- floor: documentation ( source)
<?php
$now = new DateTime('now');
$date = new DateTime('2015-05-01');
// Total difference in days
$total_days = date_diff($now, $date)->format('%a');
// Get weeks
$weeks = floor($total_days / 7);
// Get days
$days = $total_days % 7;
echo $weeks . ' weeks and ' . $days . ' days ago';