Difference between two dates in PHP

<?php
$date1 = "2015-01-23 00:20";
$date2 = "2015-01-23 05:30";
$seconds = strtotime($date2) - strtotime($date1);
$days    = floor($seconds / 86400);
$hours   = floor(($seconds - ($days * 86400)) / 3600);
$minutes = floor(($seconds - ($days * 86400) - ($hours * 3600))/60);
$seconds = floor(($seconds - ($days * 86400) - ($hours * 3600) - ($minutes*60)));
echo "$days Days, $hours Hrs $minutes mins $seconds sec";
?>