Das PHP Script Verzeichnis
function StringSizeToBytes($Size){

$Unit = strtolower($Size);
$Unit = preg_replace('/[^a-z]/', '', $Unit);
$Value = intval(preg_replace('/[^0-9]/', '', $Size));
$Units = array('b'=>0, 'kb'=>1, 'mb'=>2, 'gb'=>3, 'tb'=>4);
$Exponent = isset($Units[$Unit]) ? $Units[$Unit] : 0;

return ($Value * pow(1024, $Exponent));
}[/php]
Beispiel

// Example usage:
// Check if a file is bigger than 10 MB

if (filesize('example.zip') > StringSizeToBytes('10 MB')){
print 'File is to big !';
}
else {
print 'File is okay';
}[/php]
Quelle