Convert CIDR notation into network address, subnet mask, broadcast address and usable host count.
CIDR (Classless Inter-Domain Routing) notation combines an IP address with a prefix length that states how many leading bits form the network portion. The remaining bits identify hosts within that network. The network address is found by ANDing the IP with the mask derived from the prefix, and the broadcast address is the network ORed with the inverse mask. Usable hosts are the total addresses in the block minus the network and broadcast addresses (2^(32−prefix) − 2), except for the /31 point-to-point (RFC 3021) and /32 host-route special cases.
Usable hosts from prefix
hosts = 2^(32 − prefix) − 2
CIDR notation writes an IP address followed by a slash and a number (e.g. 192.168.1.0/24), where the number is the count of leading bits that make up the network portion of the address.
Usable hosts = 2^(32 − prefix) − 2. The subtraction removes the network address and the broadcast address, which cannot be assigned to hosts. /31 subnets (point-to-point links) and /32 (single host) are exceptions per RFC 3021.
The prefix counts network bits; fewer network bits leaves more host bits, which doubles the address space for every bit removed. A /23 has twice the addresses of a /24.
No — any address inside the block works. The calculator ANDs your address with the derived mask to find the actual network address for you.