How do I add 24 hours to a unix timestamp in php?

Question

You probably want to add one day rather than 24 hours. Not all days have 24 hours due to (among other circumstances) daylight saving time:

strtotime('+1 day', $timestamp);

A Unix timestamp is simply the number of seconds since January the first 1970, so to add 24 hours to a Unix timestamp we just add the number of seconds in 24 hours. (24 * 60 *60)

time() + 24*60*60;

Add 24*3600 which is the number of seconds in 24Hours

Unix timestamp is in seconds, so simply add the corresponding number of seconds to the timestamp:

$timeInFuture = time() + (60 * 60 * 24);

You could use the DateTime class as well:

$timestamp = mktime(15, 30, 00, 3, 28, 2015);

$d = new DateTime();
$d->setTimestamp($timestamp);

Add a Period of 1 Day:

$d->add(new DateInterval('P1D'));
echo $d->format('c');

See DateInterval for more details.

As you have said if you want to add 24 hours to the timestamp for right now then simply you can do:

 <?php echo strtotime('+1 day'); ?>

Above code will add 1 day or 24 hours to your current timestamp.

in place of +1 day you can take whatever you want, As php manual says strtotime can Parse about any English textual datetime description into a Unix timestamp.

examples from the manual are as below:

<?php
     echo strtotime("now"), "\n";
     echo strtotime("10 September 2000"), "\n";
     echo strtotime("+1 day"), "\n";
     echo strtotime("+1 week"), "\n";
     echo strtotime("+1 week 2 days 4 hours 2 seconds"), "\n";
     echo strtotime("next Thursday"), "\n";
     echo strtotime("last Monday"), "\n";
?>

$time = date("H:i", strtotime($today . " +5 hours +30 minutes"));
//+5 hours +30 minutes     Time Zone +5:30 (Asia/Kolkata)