Enter an IPv4 address and CIDR prefix to get the network address, broadcast address, subnet mask, and usable host range. Runs locally in your browser.
CIDR (Classless Inter-Domain Routing) notation writes a subnet as an IP address plus a slash and a prefix length, like 192.168.1.0/24. The prefix tells you how many of the 32 bits are fixed for the network — the rest are available for host addresses.
| CIDR | Subnet mask | Usable hosts |
|---|---|---|
| /24 | 255.255.255.0 | 254 |
| /25 | 255.255.255.128 | 126 |
| /28 | 255.255.255.240 | 14 |
| /30 | 255.255.255.252 | 2 |
The network address (first address in the range) identifies the subnet itself and can't be assigned to a device. The broadcast address (last address) sends a packet to every host on that subnet — it can't be assigned either.
A /24 has 256 total addresses, but the first (network) and last (broadcast) are reserved, leaving 254 for actual devices.
A wildcard mask is the inverse of a subnet mask. Cisco access control lists and some routing configs use it instead of a standard mask to define address ranges.
A /31 has no usable host range in the traditional sense — it's used for point-to-point links (RFC 3021). A /32 identifies a single host with no other addresses in the subnet.
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