IPv4 subnet calculator
Network, broadcast, usable host range, mask, and wildcard for any IPv4 address and prefix, with special-range detection.
How it works
Accepts address/prefix (10.0.0.0/16) or an address with a dotted mask (10.0.0.0 255.255.0.0). Octets with leading zeros are rejected because some systems read them as octal.
/31 networks are treated as point-to-point links where both addresses are usable (RFC 3021), and /32 as a single host.
The wildcard mask is the inverse of the subnet mask, as used in ACLs on many network devices.