Subnet Calculator — CIDR, Mask & Host Range Online
Calculate IPv4 and IPv6 subnets: CIDR prefix, network/broadcast, first/last usable hosts, wildcard mask, and binary breakdown. Free local subnet calculator.
Frequently asked questions
No. Addresses you enter stay in-browser. Nothing is sent to LocalTools servers for processing.
It performs CIDR math; always confirm allocations against your network engineering standards.