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Subnet Calculator

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

By CalcHub Editorial · Last reviewed

Quick answer

  • Formula: Network = IP AND mask; Broadcast = Network OR (NOT mask); Hosts = 2^(32 − prefix)
  • Worked example — Network address: 192.168.1.0 (full example below).

Subnet Calculator

Worked example result
Network address192.168.1.0
Broadcast address192.168.1.255
First usable host192.168.1.1
Last usable host192.168.1.254
Total addresses256
Usable hosts254
Subnet mask255.255.255.0
Wildcard mask0.0.0.255

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.

Diagram: how the Subnet Calculator works — you enter IPv4 address, CIDR prefix length; it applies the formula Network = IP AND mask; Broadcast = Network OR (NOT mask); Hosts = 2…; and the worked example gives Network address: 192.168.1.0.
How the Subnet Calculator works — the inputs, the formula, and a worked example (Network address: 192.168.1.0).

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.

Worked example for the Subnet Calculator: with IPv4 address 192.168.1.10, CIDR prefix length 24, the result is Network address: 192.168.1.0; Broadcast address: 192.168.1.255.
The worked example, with the example values entered and the results they give.

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

Sources & methodology

This calculator applies the formula shown on this page exactly as written, using the standard definitions for its inputs. Results are computed from the values you enter — no data is stored — and are rounded only for display.

Content last reviewed by CalcHub Editorial.

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