if($file->size>1024 && $file->size< 1024*1000){
   $file->size /= 1024;
   $file->size =round($file->size)." ko"; 
}elseif($file->size>=1024*1000 && $file->size< 1024*10000){
   $file->size /= 1024 * 1000;
   $file->size =round($file->size)." Mo";
}else{
   $file->size /= 1024 * 10000;
   $file->size =round($file->size)." Go";
}