php - Time calculation between two timestamps


I have two timestamps provided by time() and stored in database as varchar.

Now I want to calculate the difference between two times; one is1366627990, and the other one$time2=time();.

I used a script

function dateDiff($time1, $time2, $precision = 3) {
    // If not numeric then convert texts to unix timestamps
    if (!is_int($time1)) {
      $time1 = strtotime($time1);
    if (!is_int($time2)) {
      $time2 = strtotime($time2);

    // If time1 is bigger than time2
    // Then swap time1 and time2
    if ($time1 > $time2) {
      $ttime = $time1;
      $time1 = $time2;
      $time2 = $ttime;

    // Set up intervals and diffs arrays
    $intervals = array('year','month','day','hour','minute','second');
    $diffs = array();

    // Loop thru all intervals
    foreach ($intervals as $interval) {
      // Set default diff to 0
      $diffs[$interval] = 0;
      // Create temp time from time1 and interval
      $ttime = strtotime("+1 " . $interval, $time1);
      // Loop until temp time is smaller than time2
      while ($time2 >= $ttime) {
    $time1 = $ttime;
    // Create new temp time from time1 and interval
    $ttime = strtotime("+1 " . $interval, $time1);

    $count = 0;
    $times = array();
    // Loop thru all diffs
    foreach ($diffs as $interval => $value) {
      // Break if we have needed precission
      if ($count >= $precision) {
      // Add value and interval 
      // if value is bigger than 0
      if ($value > 0) {
    // Add s if value is not 1
    if ($value != 1) {
      $interval .= "s";
    // Add value and interval to times array
    $times[] = $value . " " . $interval;

    // Return string with times
    return implode(", ", $times);

and I call the function as

echo dateDiff("1366627990",$time2, 3);

but it's giving me

43 years, 3 months, 22 days

while the time should not exceed maximum of10 days.

Is there something wrong with my script?




Well, first just grab the intval() of the two timestamps, subtract one from the other and take the absolute value of the result. You'll end up with the total number of seconds between the two times.

Then use one of these examples to convert that number (of seconds) to something human readable:

seconds to minutes and days to weeks




First of all, don't expect the difference to be less than 10 days. It's 31 years:

echo date("r", 366627990); // your first time. Fri, 14 Aug 1981 09:06:30 +0000
echo date("r", 1366971706); // $time2 in my case. Fri, 26 Apr 2013 10:21:46 +0000


Okay, now you've corrected the date to1366627990. That's a difference of 4 days:

echo date("r", 1366627990); // updated time. Mon, 22 Apr 2013 10:53:10 +0000

But the solutions provided in this answer are still correct and are valid for your old and new timestamp (as well as for any other two timestamps :-) ).

Now let me get to the problem in your script and then show you a much better alternative for calculating time and date differences.

Fixing your script

The problem is your "If not numeric then convert texts to unix timestamps" check in the beginning. Because this won't work if you pass UNIX timestamps as strings, which you apparently do. A hack that fixes this would be to include the following at the beginning of the function:

function dateDiff($time1, $time2, $precision = 3) {
    // hack for passing timestamps as strings
    if ($time1 == intval($time1)) {
        $time1 = intval($time1);
    if ($time2 == intval($time2)) {
        $time2 = intval($time2);

Now, your function yields the correct output:

31 years, 8 months, 12 days

A better way for calculating time intervals

As of version 5.2.0, PHP has the super-neat with a diff method, which is exactly what you need:

$d1 = new DateTime();
$d2 = new DateTime();

$diff = $d1->diff($d2);

echo $diff->format("%y years, %m months, %d days");

This one also gives you

31 years, 8 months, 12 days




    $time1 = (int)1366971673; //The value of time() when I wrote this.
    $time2 = (int)1366627990; //Your time value to compare.

    $diff = (int)$time1-$time2;

    echo round(($diff/60/60/24)).' days between dates.';

Should output;

4 days between dates.

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