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IPv4 Subnet Calculator

Plan an IPv4 network from an address and CIDR prefix such as 192.168.1.0/24. Get the network and broadcast address, first and last host, total addresses, usable host count, subnet mask and wildcard mask with no network lookup.

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Try 192.168.1.0/24 or 10.0.0.0/8.

How to use the Subnet Calculator

  1. 1 Enter an IPv4 address and CIDR prefix, for example 10.0.0.0/8.
  2. 2 Run the calculation to normalize the network address.
  3. 3 Use the network, broadcast, host range and mask values when planning the subnet.

Frequently asked questions

What is CIDR notation?

CIDR combines an IPv4 address with a prefix length, such as /24. The prefix says how many leading bits identify the network; the remaining bits identify addresses inside it.

Does this subnet calculator query my IP or a server?

No. It only calculates the address you enter in your browser and makes no network request.

How are usable hosts counted for /31 and /32?

This calculator reports the conventional host count: /31 has two addresses for point-to-point use and /32 has one address; smaller prefixes reserve network and broadcast addresses.

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