<?PHP
 
// calculate.directory.class.php
// Credits: BitRepository.com
// URL: http://www.bitrepository.com/web-programming/php/
// calculate-the-size-number-of-files-folders-of-a-directory.html
 
 
CLASS Directory_Calculator {
 
    VAR $size_in;
     VAR $decimals;
 
    FUNCTION calculate_whole_directory($directory)
    {
        IF ($handle = OPENDIR($directory))
        {
        $size = 0;
          $folders = 0;
          $files = 0;
 
        WHILE (FALSE !== ($file = READDIR($handle)))
          {
            IF ($file != "." && $file != "..")
               {
                   IF(IS_DIR($directory.$file))
                   {
                $array = $this->calculate_whole_directory($directory.$file.'/');
                $size += $array['size'];
                    $files += $array['files'];
                    $folders += $array['folders'];
                   }
                   ELSE
                   {
                $size += FILESIZE($directory.$file);
                    $files++;
                   }
            }
         }
         CLOSEDIR($handle);
         }
 
           $folders++;
 
    RETURN ARRAY('size' => $size, 'files' => $files, 'folders' => $folders);
    }
 
     FUNCTION size_calculator($size_in_bytes)
    {
        IF($this->size_in == 'B')
        {
        $size = $size_in_bytes;
        }
        ELSEIF($this->size_in == 'KB')
        {
        $size = (($size_in_bytes / 1024));
        }
        ELSEIF($this->size_in == 'MB')
        {
        $size = (($size_in_bytes / 1024) / 1024);
        }
        ELSEIF($this->size_in == 'GB')
        {
        $size = (($size_in_bytes / 1024) / 1024) / 1024;
        }
 
        $size = ROUND($size, $this->decimals);
 
          RETURN $size;
     }
 
     FUNCTION size($directory)
     {
     $array = $this->calculate_whole_directory($directory);
     $bytes = $array['size'];
     $size = $this->size_calculator($bytes);
     $files = $array['files'];
     $folders = $array['folders'] - 1; // exclude the main folder
 
     RETURN ARRAY('size'    => $size,
                   'files'   => $files,
                   'folders' => $folders);
     }
}
?>
 
Here’s an usage example of this class:
 
example.php
 
<?PHP
SET_TIME_LIMIT(10000);
 
INCLUDE 'calculate.directory.class.php';
 
/* Path to Directory - IMPORTANT: with '/' at the end */
 
$directory = '/home/mywebsite.com/public_html/'; 
 
/* Calculate size in: B (Bytes), KB (Kilobytes), MB (Megabytes), GB (Gigabytes) */
 
$size_in = 'MB';
 
/* Number of decimals to show */
 
$decimals = 2;
 
$directory_size = NEW Directory_Calculator;
 
/* Initialize Class */
 
$directory_size->size_in = $size_in;
$directory_size->decimals = $decimals;
 
// return an array with: size, total files & folders
$array = $directory_size->size($directory); 
 
ECHO "The directory <em>".$directory."</em> has a size of 
     ".$array['size']." ".$size_in.", ".$array['files']." files & 
     ".$array['folders']." folders.";
?>