Rangdom

Break an IPv4 subnet into its network details

Enter any IPv4 address and a prefix length (such as /24) or an equivalent dotted netmask (such as 255.255.255.0). The network and broadcast addresses, subnet and wildcard masks, usable host range, and address counts update live as you type.

For /0–/30 the usable host count is 2^(32 − n) − 2, reserving the network and broadcast addresses. A /31 is a two-address point-to-point link pair and a /32 is a single host, so both report 0 usable hosts under the conventional model.