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Networking

Subnet Calculator

Find the network, address range and subnet mask for an IPv4 address.

Calculations run in your browser. The tool does not send your inputs to a server.

01Your inputs

Local workspace

Start with the sample below, or enter your own values.

Enter an IPv4 address with /0 through /32, for example 192.168.10.42/24. The result finds the containing network; /1 covers half the IPv4 address space, while /32 is one address.

02Your result

Your result will appear here. Choose an action after checking your inputs.

A quick guide

How to use this tool

  1. Check the example and the unit beside each input.
  2. Enter your values and choose Calculate.
  3. Review the result and assumptions, then copy what you need.

Reset example restores the starting values. Clear removes text and number inputs, returns choices to their first valid option, and removes the result.

Reference guide

Explanation and worked examples

For 192.168.10.42/24, the network is 192.168.10.0 and there are 254 conventional usable host addresses. The diagram separates network bits from host bits.

Use in day-to-day IT work

Check whether a VLAN subnet has room for devices, its gateway and future growth.

Checks before applying the result

  • A /26 contains 64 addresses and normally 62 host addresses. Subtract gateways, reservations and vendor-reserved addresses from that host allowance.
  • A /31 is for compatible point-to-point links; a /32 identifies one address. Neither has a conventional broadcast address.
New to the terminology?
CIDR
An address block written with a slash and prefix length, such as /24.
Prefix
The number of address bits fixed to identify a network.
Mbps
Millions of bits per second. Divide by eight to compare with MB/s.

Keep exploring

CIDR SplitterIP Range to CIDRVLSM CalculatorWildcard Mask CalculatorLearn Subnetting →

How calculations work and where the models stop →