Example: 10.0.0.0 with /8, or 203.0.113.50/29—any host address in the block works.
Enter any IPv4 inside the subnet and a prefix length (0–32). Outputs mask, network, broadcast, and host range.
Example: 10.0.0.0 with /8, or 203.0.113.50/29—any host address in the block works.
Given an IPv4 address and a CIDR prefix 0–32, the page derives the subnet mask, wildcard mask, network address, broadcast, first/last host, total addresses, and a usable-host estimate. /32 is treated as a single host; /31 follows RFC 3021 point-to-point semantics; other prefixes use the classic “−2” usable count unless noted for /0. If your typed address is not the network ID, the note explains you are still inside that subnet.
This calculator uses plain decimal numbers. If a result looks wrong, check whether you used a comma instead of a dot (or vice versa) where the field expects one.