<?php
$time1 = new DateTime('20150501');
$time2 = new DateTime(); //data atual
$interval = $time2->diff($time1);
echo $interval->days;
PD9waHAKCiR0aW1lMSA9IG5ldyBEYXRlVGltZSgnMjAxNTA1MDEnKTsgCiR0aW1lMiA9IG5ldyBEYXRlVGltZSgpOyAvL2RhdGEgYXR1YWwKJGludGVydmFsID0gICR0aW1lMi0+ZGlmZigkdGltZTEpOwplY2hvICRpbnRlcnZhbC0+ZGF5czs=