<?php
list($width, $height) = getimagesize($filename);
$imgsize = filesize($filename)/1024;
$imgsize2 = round($imgsize, 0);

//Prints something like 153 KB.
echo $imgsize2." KB";
?>






function getfilesize($bytes) {
   if ($bytes >= pow(2,40)) {
       $return = round($bytes / pow(1024,4), 2);
       $suffix = "TB";
   } elseif ($bytes >= pow(2,30)) {
       $return = round($bytes / pow(1024,3), 2);
       $suffix = "GB";
   } elseif ($bytes >= pow(2,20)) {
       $return = round($bytes / pow(1024,2), 2);
       $suffix = "MB";
   } elseif ($bytes >= pow(2,10)) {
       $return = round($bytes / pow(1024,1), 2);
       $suffix = "KB";
   } else {
       $return = $bytes;
       $suffix = "Byte";
   }
   if ($return == 1) {
       $return .= " " . $suffix;
   } else {
       $return .= " " . $suffix . "s";
   }
   return $return;
}
echo getfilesize(pow(2,30));