subtract to dates ad return days php as dates code example
Example 1: php get day diff
$now = time(); // or your date as well
$your_date = strtotime("2010-01-31");
$datediff = $now - $your_date;
echo round($datediff / (60 * 60 * 24));
Example 2: substract 2 dates php
$datetime1 = strtotime('May 3, 2012 10:38:22 GMT');
$datetime2 = strtotime('06 Apr 2012 07:22:21 GMT');
$secs = $datetime2 - $datetime1;// == <seconds between the two times>
$days = $secs / 86400;