Subnet Calculator

Network, broadcast, usable hosts and masks for an IPv4 CIDR block.

Subnet Calculator

Worked example result

Network address	192.168.1.0
Broadcast address	192.168.1.255
First usable host	192.168.1.1
Last usable host	192.168.1.254
Total addresses	256
Usable hosts	254
Subnet mask	255.255.255.0
Wildcard mask	0.0.0.255

192.168.1.10/24 sits in network 192.168.1.0 with broadcast 192.168.1.255 and 254 usable hosts, .1 through .254.

Enter an IPv4 address and a CIDR prefix length to get the network address, broadcast address, first and last usable host addresses, the subnet and wildcard masks, and the host counts for the block.

For prefixes /0 to /30, two addresses per block are reserved (network and broadcast), leaving total − 2 usable hosts. The special cases follow common practice: a /31 point-to-point link has 2 usable addresses and a /32 is a single host route.

The formula

Network = IP AND mask; Broadcast = Network OR (NOT mask); Hosts = 2^(32 − prefix)

Worked example

192.168.1.10/24 sits in network 192.168.1.0 with broadcast 192.168.1.255 and 254 usable hosts, .1 through .254.

The example is pre-loaded in the result panel — press Calculate with your own numbers to replace it.

Frequently asked questions

Why does a /24 have 254 usable hosts, not 256?

A /24 block has 2^8 = 256 addresses, but the first is the network address and the last is the broadcast address, leaving 254 for hosts.

What is a wildcard mask used for?

It is the bitwise inverse of the subnet mask and is used in router ACLs and OSPF statements, where 0 bits mean 'must match' and 1 bits mean 'ignore' — the opposite convention to a subnet mask.

Category: Everyday Life calculators

Subnet Calculator