CIDR calculator
IPv4 / IPv6Turn an address and prefix into its exact network, mask, range, host counts, and optional subnet split.
Enter a CIDR network to beginTry 192.168.1.10/24 with a /26 split, or an IPv6 prefix such as 2001:db8::/48.
How CIDR calculations work
The prefix length identifies the fixed network bits. The remaining bits form the address range. IPv4 normally reserves the network and broadcast addresses, except that /31 point-to-point networks and /32 host routes use every address.
IPv6 has no broadcast address, so this calculator treats the complete range as usable while leaving interface and protocol-specific reservations to your network design.