<?php

function fsize($path)
{
$fp = fopen($path,"r");
$inf = stream_get_meta_data($fp);
fclose($fp);
foreach($inf["wrapper_data"] as $v)
if (stristr($v,"content-length"))
{
$v = explode(":",$v);
return trim($v[1]);
}
}

$filesize = "http://www.html.by/images/top_html.jpg";
echo fsize($filesize);

?>

<?php

$filename = "www.html.by/index.php";
$fh = fopen($filename, "r");
while(($str = fread($fh, 1024)) != null) $fsize += strlen($str);

echo "Размер файла: ".$fsize;

?>