SubnetMath is an IPv4 subnet calculator that shows netmask, wildcard, network, broadcast and host range, splits networks and converts IP ranges to CIDR blocks — with no account.
It was built to be fast and private. There are no accounts and no uploads; every calculation happens in your browser. The site may be supported by unobtrusive advertising, which never appears inside the tool itself.
Spotted a bug or want a new feature? Get in touch.