- strtotime: documentation ( source)
<?php
echo strtotime('+48 hours', null);
echo "
";
echo strtotime('+48 hours', 0);
echo "
";
echo strtotime('+48 hours', strtotime('2015-05-06 11:41:30'));
echo "
";
if (strtotime('2015-05-06 12:50:30') < strtotime('+48 hours', strtotime('2015-05-06 11:41:30'))) {
echo 'test';
}