Remote file size without downloading file

Question

Is there a way to get the size of a remote file http://my_url/my_file.txt without downloading the file?

Answer 1

one line best solution :

echo array_change_key_case(get_headers("http://.../file.txt",1))['content-length'];

php is too delicius

function urlsize($url):int{
   return array_change_key_case(get_headers($url,1))['content-length'];
}

echo urlsize("http://.../file.txt");

Answer 2

As mentioned a couple of times, the way to go is to retrieve the information from the response header's Content-Length field.

However, you should note that

• the server you're probing not necessarily implements the HEAD method(!)
• there's absolutely no need to manually craft a HEAD request (which, again, might not even be supported) using fopen or alike or even to invoke the curl library, when PHP has get_headers() (remember: K.I.S.S.)

Use of get_headers() follows the K.I.S.S. principle and works even if the server you're probing does not support the HEAD request.

So, here's my version (gimmick: returns human-readable formatted size ;-)):

Gist: https://gist.github.com/eyecatchup/f26300ffd7e50a92bc4d (curl and get_headers version)
get_headers()-Version:

<?php     
/**
 *  Get the file size of any remote resource (using get_headers()), 
 *  either in bytes or - default - as human-readable formatted string.
 *
 *  @author  Stephan Schmitz <eyecatchup@gmail.com>
 *  @license MIT <http://eyecatchup.mit-license.org/>
 *  @url     <https://gist.github.com/eyecatchup/f26300ffd7e50a92bc4d>
 *
 *  @param   string   $url          Takes the remote object's URL.
 *  @param   boolean  $formatSize   Whether to return size in bytes or formatted.
 *  @param   boolean  $useHead      Whether to use HEAD requests. If false, uses GET.
 *  @return  string                 Returns human-readable formatted size
 *                                  or size in bytes (default: formatted).
 */
function getRemoteFilesize($url, $formatSize = true, $useHead = true)
{
    if (false !== $useHead) {
        stream_context_set_default(array('http' => array('method' => 'HEAD')));
    }
    $head = array_change_key_case(get_headers($url, 1));
    // content-length of download (in bytes), read from Content-Length: field
    $clen = isset($head['content-length']) ? $head['content-length'] : 0;

    // cannot retrieve file size, return "-1"
    if (!$clen) {
        return -1;
    }

    if (!$formatSize) {
        return $clen; // return size in bytes
    }

    $size = $clen;
    switch ($clen) {
        case $clen < 1024:
            $size = $clen .' B'; break;
        case $clen < 1048576:
            $size = round($clen / 1024, 2) .' KiB'; break;
        case $clen < 1073741824:
            $size = round($clen / 1048576, 2) . ' MiB'; break;
        case $clen < 1099511627776:
            $size = round($clen / 1073741824, 2) . ' GiB'; break;
    }

    return $size; // return formatted size
}

Usage:

$url = 'http://download.tuxfamily.org/notepadplus/6.6.9/npp.6.6.9.Installer.exe';
echo getRemoteFilesize($url); // echoes "7.51 MiB"

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Additional note: The Content-Length header is optional. Thus, as a general solution it isn't bullet proof!

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