Subnet Calculator

Calculate IPv4 and IPv6 subnet ranges, prefix lengths and address counts. Supports IPv4 dotted masks and IPv6 /0–/128 locally in your browser.

How to use Subnet Calculator

Enter IPv4 with CIDR or a dotted mask, or IPv6 with a prefix such as 2001:db8::/64. IPv4 keeps its class-based and CIDR modes; IPv6 supports /0–/128 and has no address classes.

Understanding the results

Review the network, address range and exact address count. IPv6 has no broadcast address; its address count is not a usable-host or routability guarantee. All subnet calculations run locally.

Can I calculate private IPv4 and IPv6 subnets?

Yes. The calculator accepts network addresses rather than domain names and performs calculations locally. Address counts describe the subnet size; they do not establish public reachability.