IP Subnet / CIDR Calculator

Calculate IPv4 network details from CIDR notation: network and broadcast addresses, usable host range, subnet mask, and wildcard mask. All math happens in your browser.

CIDR (Classless Inter-Domain Routing) notation describes an IP network as an address plus a prefix length, like 10.0.0.0/16. This calculator derives the network and broadcast addresses, the usable host range and count, the dotted-decimal and binary subnet masks, and the wildcard mask used in ACLs. It handles the /31 point-to-point (RFC 3021) and /32 host-route special cases. Useful for planning VPCs, firewall rules, and on-prem subnets.