Converting To And From Decimal Time In PHP

To convert a time value into a decimal value representing the number of minutes can be useful for certain calculations. The following function takes a time as a string of hh:mm:ss and returns a decimal value in minutes.

/**


 * Convert time into decimal time.


 *


 * @param string $time The time to convert


 *


 * @return integer The time as a decimal value.


 */


function time_to_decimal($time) {


    $timeArr = explode(':', $time);


    $decTime = ($timeArr[0]*60) + ($timeArr[1]) + ($timeArr[2]/60);


 


    return $decTime;


}

If we take the time of 11:11:11 this gets split into 3 parts by the explode() function into hours, minutes and seconds, which then gets treated in the following way:

Minutes = (Hours x 60) + (Minutes) + (Seconds / 60)


Minutes = (11 x 60) + (11) + (11 / 60)


Minutes = (660) + (11) + (0.18333333)


Minutes = 671.18333333

The function can be used as follows:

echo time_to_decimal("11:11:11"); // prints 671.18333333

The reverse of this function takes the decimal value and returns a string in the format hh:mm:ss.

/**


 * Convert decimal time into time in the format hh:mm:ss


 *


 * @param integer The time as a decimal value.


 *


 * @return string $time The converted time value.


 */


function decimal_to_time($decimal) {


    $hours = floor($decimal / 60);


    $minutes = floor($decimal % / 60);


    $seconds = $decimal - (int)$decimal;


    $seconds = round($seconds * 60);


 


    return str_pad($hours, 2, "0", STR_PAD_LEFT) . ":" . str_pad($minutes, 2, "0", STR_PAD_LEFT) . ":" . str_pad($seconds, 2, "0", STR_PAD_LEFT);


}

This function can be used as follows:

echo decimal_to_time(671.18333333); // prints 11:11:11

Note that these functions deal with amounts of time, not the time of day. Converting between time and decimal time of day requires a different set of calculations.

UPDATE: Thanks to an anonymous poster for pointing out some errors, these have now been corrected.

Your code indeed works in the manner you have described, however there are a couple of finer details that caused issues for me when using the code.

In the time_to_decimal function, line 12 should read as follows:

$decTime = ($timeArr[0]*60) + ($timeArr[1]) + ($timeArr[2]/60);

As it is written in your post, the seconds are actually representing fractions of an hour (1/3600th) as opposed to fractions of a minute (1/60th). 

We have the same issue in the decimal_to_time function as well as an issue in regards to the round() function.  I've corrected the decimal_to_time function as follows:

function decimal_to_time($decimal) {


    $hours = floor((int)$decimal / 60);


    $minutes = floor((int)$decimal % 60);


    $seconds = $decimal - (int)$decimal; 


    $seconds = round($seconds * 60); 


 


    return str_pad($hours, 2, "0", STR_PAD_LEFT) . ":" . str_pad($minutes, 2, "0", STR_PAD_LEFT) . ":" . str_pad($seconds, 2, "0", STR_PAD_LEFT);


}

round() in lines 2 and 3 have been replaced by floor().  This is due to the behavior of round() returning 1 when given .5.  An example is as follows:

Say we are converting 1:30:30 into a decimal representing minutes.  Using the two functions posted we would have

echo time_to_decimal('1:30:30'); // prints 90.008333333333, seconds are still converted incorrectly


 


// this should display the input from the first function


echo decimal_to_time(90.008333333333); // prints 02:02:30, not correct

In the example, line 2 of the original code calculates to - round( 90 / 60 ) = round(1.5) = 2.  Since we only want the numer of whole hours in the $decimal variable, we should use floor() instead.  floor() will always round to the lowest whole number ( 1 in this case )

I hope this helps someone out there :)

i propose to change little to allow this kind of input "01:05" =1h05 or "01:05:00" or "01"=1hour

 function time_to_decimal($time) {


  $timeArr = explode(':', $time);


  if (count($timeArr) == 3) {


   $decTime = ($timeArr[0]*60) + ($timeArr[1]) + ($timeArr[2]/60);  


  } else if (count($timeArr) == 2) {


   $decTime = ($timeArr[0]) + ($timeArr[1]/60);


  } else if (count($timeArr) == 2) {


   $decTime = $time; 


  }


  return $decTime;


 }

This function kept returning :60 in the seconds place! I added :

if ($seconds == 60) {


         $minutes++;


         $seconds=0;


         }

to the end of the function.

My 2 cents comment if used your function and added a format control to avoid strange behavior and surprise

   function Time_To_Decimal($time) {


      $decTime = 0;


      if (preg_match("/^([01][0-9]|2[0-3]):([0-5][0-9]):([0-5][0-9])$/", $time, $matches)) {


         $decTime = ($matches[0]*60) + ($matches[1]) + ($matches[2]/60);


      }   


      return $decTime;


   }

Sorry posted too quickly (fixed preg_match return array)

   function Time_To_Decimal($time) {


      $decTime = 0;


      if (preg_match("/^([01][0-9]|2[0-3]):([0-5][0-9]):([0-5][0-9])$/", $time, $matches)) {


         $decTime = ($matches[1]*60) + ($matches[2]) + ($matches[3]/60);


      }   


      return $decTime;


   }