Subnet / IP Calculator
Calculate network, broadcast, usable host range and mask for any IPv4 CIDR.
How to use this tool
Enter an IPv4 address and a prefix length (for example 192.168.10.37/26). The calculator returns the network address, broadcast address, first and last usable host, subnet mask, wildcard mask and the number of usable hosts. Use it before assigning VLAN ranges or writing firewall rules.
Worked example
192.168.10.37/26 gives network 192.168.10.0, broadcast 192.168.10.63, usable hosts 192.168.10.1 – 192.168.10.62 (62 hosts), mask 255.255.255.192.
Frequently asked questions
How many usable hosts are in a /24?
A /24 has 256 addresses, of which 254 are usable (the network and broadcast addresses are reserved).
What is a wildcard mask?
It is the inverse of the subnet mask (for /24: 0.0.0.255). Cisco ACLs and OSPF network statements use it.
Why does a /31 show 2 hosts?
RFC 3021 allows /31 on point-to-point links, so both addresses are usable and there is no broadcast address.