About this subnet calculator
Enter an IPv4 address and a prefix length or subnet mask. The calculator ANDs the address with the mask to get the network address, sets the host bits to get the broadcast, and lists the usable range between them. A /24 gives 256 addresses and 254 usable hosts; each bit you add to the prefix halves the block. It also shows the wildcard mask used in ACLs and OSPF, the mask in binary, the historical class, and whether the address is private (RFC 1918), loopback, link-local or public.