CIDR calculator

Calculate network boundaries locally for IPv4 or IPv6. The prefix length states how many bits identify the network. No provider or JavaScript is needed.

For example, 192.0.2.10/24 or 2001:db8::1/64.

First and last addresses are inclusive boundaries, not a count of assignable hosts. IPv4 host usability depends on the subnet and context; IPv6 has no broadcast address. Total addresses includes every address in the prefix.

What is CIDR notation? · Private IP addresses