Get network, broadcast, usable host range, netmask and wildcard from any IPv4 address and CIDR prefix — in your browser.
CIDR (Classless Inter-Domain Routing) is how IPv4 networks have been described since 1993: an address followed by a slash and a prefix length, like 192.168.1.10/24. The prefix says how many of the 32 bits identify the network; the remaining bits identify hosts inside it. From that single piece of information this calculator derives everything a network plan needs — the network address, the broadcast address, the range of usable hosts, the subnet mask in dotted-decimal form and its inverse, the wildcard mask.
Under the hood the tool converts the address to a 32-bit unsigned integer and applies the same bitwise operations a router applies: the network address is the IP AND the mask, the wildcard is the inverted mask, and the broadcast is the network OR the wildcard. For prefixes up to /30, two addresses in every subnet are reserved — the network itself and the broadcast — so the usable host count is 2 to the power of (32 minus prefix), minus 2. The edge cases are handled correctly too: a /31 is a point-to-point link where both addresses are usable (RFC 3021), and a /32 pins down a single host.
This is the calculation behind everyday networking tasks: splitting an office network into VLANs, sizing a DHCP pool, writing firewall rules, or building Cisco-style access lists — which is exactly what the wildcard mask output is for. It is also a solid study companion for CCNA-style certification questions, since the explanation shows the intermediate values instead of just the answer, plus a quick reference of common prefixes from /8 to /30. All of the arithmetic runs 100% in your browser; no address you type is looked up, logged or transmitted.
Network = IP AND mask; wildcard = NOT mask; broadcast = network OR wildcard; usable hosts = 2^(32 − prefix) − 2 for prefixes up to /30. Example: 192.168.1.10/24 → network 192.168.1.0, broadcast 192.168.1.255, 254 usable hosts.
254. A /24 spans 256 addresses, but the first one (the network address) and the last one (the broadcast address) are reserved, leaving 254 for devices — for 192.168.1.0/24 that is 192.168.1.1 through 192.168.1.254.
Because the all-zeros host part identifies the network itself and the all-ones host part is the broadcast address that reaches every device in the subnet. Neither can be assigned to a machine, except in the special /31 and /32 cases.
It is the bit-inverted subnet mask, used mainly in Cisco access control lists and OSPF configuration: a 0 bit means "must match" and a 1 bit means "ignore". For a /24, mask 255.255.255.0 becomes wildcard 0.0.0.255.
Yes. A /31 is treated as a point-to-point link with 2 usable addresses, as defined by RFC 3021, and a /32 is reported as a single-host route. Both are common in router configurations.
No. All the bitwise arithmetic runs in JavaScript on your device. The address is not looked up, logged or sent anywhere.
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