File size in human format

I needed to see some file sizes in a human format (in a PHP page) so I created this function some of you might find useful:

/**Returns the size of data (provided in bytes) in a human readable
 * format
 * @size - the the size of data in bytes
 * @author alex from scriptoid.com
 */
function humanSize($size){
    if($size < pow(1024, 1)){
        return $size . 'Bytes';
    }
    else if ($size < pow(1024, 2)){
        return sprintf("%.2f", $size/pow(1024, 1)) . 'Kb'; //Kilo
    }
    else if ($size < pow(1024, 3)){
        return  sprintf("%.2f", $size/pow(1024, 2)) . 'Mb'; //Mega
    }
    else if ($size < pow(1024, 4)){
        return  sprintf("%.2f",$size/pow(1024, 3)) . 'Gb'; //Giga
    }
    else if ($size < pow(1024, 5)){
        return  sprintf("%.2f",$size / pow(1024, 4)) . 'Tb'; //Tera
    }
    else if ($size < pow(1024, 6)){
        return  sprintf("%.2f",$size / pow(1024, 5)) . 'Pb'; //Peta
    }
    else if ($size < pow(1024, 7)){
        return  sprintf("%.2f",$size / pow(1024, 6)) . 'Eb'; //Exa
    }
    else if ($size < pow(1024, 8)){
        return  sprintf("%.2f",$size /pow(1024, 7)) . 'Zb'; //Zeta
    }
    else if ($size < pow(1024, 9)){
        return  sprintf("%.2f",$size /pow(1024, 8)) . 'Yb'; //Yota
    }
    else{
        return 'too big'; //:D
    }
}