php Gets the file size method

static function convert($size) { 
        $unit=array('b','kb','mb','gb','tb','pb'); 
        return @round($size/pow(1024,($i=floor(log($size,1024)))),2).' '.$unit[$i]; 
    } 

The following method can also be used

/**
 * Returns a human readable filesize
 */
function HumanReadableFilesize($size) {
    $mod = 1024; 
    $units = explode(' ','B KB MB GB TB PB');
    for ($i = 0; $size > $mod; $i++) {
        $size /= $mod;
    }
    return round($size, 2) . ' ' . $units[$i];
}