Enter an IPv4 address and CIDR prefix (or subnet mask) to get the network address, broadcast address, usable host range and a full subnetting breakdown — instantly, in your browser.
All subnet math runs in your browser with plain JavaScript. No IP address you enter is ever sent anywhere — useful even for internal or non-public network ranges.
Enter CIDR shorthand like /24, or a full dotted mask like 255.255.255.0 after the IP — both are accepted and converted automatically.
Pick a smaller prefix and instantly see every resulting subnet with its network address, usable host range and broadcast address — no manual binary math required.
10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 are reserved for private networks and never routed on the public internet — the tool flags these automatically.
Every subnet reserves its first address for the network ID and its last for the broadcast address, so usable hosts = total addresses − 2 (except for /31 and /32, which are special cases).
Calculate as many networks and subnet splits as you like — no sign-up, no rate limit, no ads blocking the results.