- date: documentation ( source)
- strtotime: documentation ( source)
<?php
$start = "10:00";
$period = "1:30";
$end = "00:30";
$date = date('Y-m-d');
$start_date = $date.' '.$start.':00';
$end_date = datetime('Y-m-d H:i:s', strtotime($start_date.' +1 day'));
echo "Start: ".$start_date."\n";
echo "End: ".$end_date."\n";