this function works for any size:
function fsize($file) {
// filesize will only return the lower 32 bits of
// the file's size! Make it unsigned.
$fmod = filesize($file);
if ($fmod < 0) $fmod += 2.0 * (PHP_INT_MAX + 1);
// find the upper 32 bits
$i = 0;
$myfile = fopen($file, "r");
// feof has undefined behaviour for big files.
// after we hit the eof with fseek,
// fread may not be able to detect the eof,
// but it also can't read bytes, so use it as an
// indicator.
while (strlen(fread($myfile, 1)) === 1) {
fseek($myfile, PHP_INT_MAX, SEEK_CUR);
$i++;
}
fclose($myfile);
// $i is a multiplier for PHP_INT_MAX byte blocks.
// return to the last multiple of 4, as filesize has modulo of 4 GB (lower 32 bits)
if ($i % 2 == 1) $i--;
// add the lower 32 bit to our PHP_INT_MAX multiplier
return ((float)($i) * (PHP_INT_MAX + 1)) + $fmod;
}
note: this function maybe litte slow for files > 2gb
(taken from php comments)