Get interval seconds between two datetime in PHP?

2009-10-05 18:11:08

2009-10-05 18:07:13

This should generate 235,how to do it ?

With DateTime objects, you can do it like this:

$date = new DateTime( '2009-10-05 18:07:13' );
$date2 = new DateTime( '2009-10-05 18:11:08' );

$diffInSeconds = $date2->getTimestamp() - $date->getTimestamp();

You can use strtotime() to do that:

$diff = strtotime('2009-10-05 18:11:08') - strtotime('2009-10-05 18:07:13')

A similar approach is possible with DateTime objects, e.g.

$date = new DateTime( '2009-10-05 18:07:13' );
$date2 = new DateTime( '2009-10-05 18:11:08' );

$diff = $date2->getTimestamp() - $date->getTimestamp();

PHP Date Time reference is helpful for things like this: PHP Date Time Functions

strtotime() is probably the best way.

$seconds = strtotime('2009-10-05 18:11:08') - strtotime('2009-10-05 18:07:13')

For those worrying about the limitations of using timestamps (i.e. using dates before 1970 and beyond 2038), you can simply calculate the difference in seconds like so:

$start = new DateTime('2009-10-05 18:11:08');
$end = new DateTime('2009-10-05 18:07:13');
$diff = $end->diff($start);

$daysInSecs = $diff->format('%r%a') * 24 * 60 * 60;
$hoursInSecs = $diff->h * 60 * 60;
$minsInSecs = $diff->i * 60;

$seconds = $daysInSecs + $hoursInSecs + $minsInSecs + $diff->s;

echo $seconds; // output: 235

Wrote a blog post for those interested in reading more.

Because of unix epoch limitations, you could have problems compairing dates before 1970 and after 2038. I choose to loose precision (=don't look at the single second) but avoid to pass trough unix epoch conversions (getTimestamp). It depends on what you are doing to do...

In my case, using 365 instead (12*30) and "30" as mean month lenght, reduced the error in an usable output.

function DateIntervalToSec($start,$end){ // as datetime object returns difference in seconds
    $diff = $end->diff($start);
    $diff_sec = $diff->format('%r').( // prepend the sign - if negative, change it to R if you want the +, too
                ($diff->s)+ // seconds (no errors)
                (60*($diff->i))+ // minutes (no errors)
                (60*60*($diff->h))+ // hours (no errors)
                (24*60*60*($diff->d))+ // days (no errors)
                (30*24*60*60*($diff->m))+ // months (???)
                (365*24*60*60*($diff->y)) // years (???)
                );
    return $diff_sec;
}

Note that the error could be 0, if "mean" quantities are intended for diff. The PHP docs don't speaks about this... In a bad case, error could be:

• 0 seconds if diff is applied to time gaps < 1 month
• 0 to 3 days if diff is applied to time gaps > 1 month
• 0 to 14 days if diff is applied to time gaps > 1 year

I prefer to suppose that somebody decided to consider "m" as 30 days and "y" as 365, charging "d" with the difference when "diff" walk trough non-30-days months...

If somebody knows something more about this and can provide official documentation, is welcome!