$time_diff = strtotime('2013-03-13 12:45:00') - strtotime('2013-03-13 11:00:00'); echo $time_diff/60;
I just set the dates as not sure if saving the temporary part will return the correct diff or not.
EDIT
I just checked that it works without a date too ...
$time_diff = strtotime('12:45:00') - strtotime('11:00:00'); echo $time_diff/60;
So, to answer your question - strtotime () returns a timestamp (the number of seconds since January 1, 1970, 00:00:00 UTC), so you just divide it by 60 to convert the result to minutes.
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