<?php
    function dirSize($directoty){
        $dir_size=0;

        if($dir_handle=@opendir($directoty))
        {
            while($filename=readdir($dir_handle)){
                $subFile=$directoty.DIRECTORY_SEPARATOR.$filename;
                if($filename=='.'||$filename=='..'){
                    continue;
                }elseif (is_dir($subFile))
                {
                    $dir_size+=dirSize($subFile);
                }elseif (is_file($subFile)){
                    $dir_size+=filesize($subFile);
                }
            }
            closedir($dir_handle);
        }
        return ($dir_size);
    }

    $dir_size=dirSize("xym");
    echo round($dir_size/pow(1024,1),2)."KB";
?>