Subnet Calculator

This calculator converts your IP address and subnet mask (or CIDR prefix) into 32-bit binary numbers, then applies a bitwise AND between the IP and the mask to find the network address, the lowest address in the range. The broadcast address is found by setting all the 'host' bits (the bits not covered by the mask) to 1.

The usable host range excludes the network address and broadcast address from a subnet, since those are reserved, except for /31 subnets (used for point-to-point links, both addresses are usable) and /32 (a single host route with exactly one address).

CIDR notation (like /24) expresses the subnet mask as a prefix length, the number of leading 1 bits in the mask. This is equivalent to a dotted-decimal mask like 255.255.255.0, this calculator accepts either format and shows both in the results, along with the wildcard mask, the inverse of the subnet mask used in access control lists on some network equipment.