$time1 = new DateTime('09:00:59');
$time2 = new DateTime('09:01:00');
$interval = $time1->diff($time2);
echo $interval->format('%s second(s)');
Result: 1 second(s) date_default_timezone_set("Africa/Johannesburg");
$now = new DateTime();
$future_date = new DateTime('2020-10-21 00:00:00');
$interval = $future_date->diff($now);
echo ($interval->format("%a") * 24) + $interval->format("%h"). " hours". $interval->format(" %i minutes ");
print_r($now->format('Y-m-d H:i:s'));
$timeFirst = strtotime('2011-05-12 18:20:20');
$timeSecond = strtotime('2011-05-13 18:20:20');
$differenceInSeconds = $timeSecond - $timeFirst;