Subnet Calculator & CIDR IP Tool
High-precision subnet calculator for IPv4 and IPv6: network range, broadcast or last address, first/last usable hosts, wildcard mask, binary breakdown, and address class. All processing is local.
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.