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Networking

CIDR Splitter

Divide an IPv4 network into equal, smaller subnets.

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 the parent IPv4 block to divide, for example 192.168.8.0/24. A /32 is one address and cannot be divided further.
Use a longer prefix for smaller children: /24 to /26 creates four subnets. A shorter prefix makes a larger block and is not a split. An equal prefix leaves the block unchanged.

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

The new prefix must be at least as long as the original. A /24 split into /26 gives four blocks of 64 addresses.

Use in day-to-day IT work

Prepare addressing or transfer estimates for a network change, migration or support ticket.

Checks before applying the result

  • Compare the result with IPAM, VLAN boundaries, routes and DHCP reservations before allocating addresses.
  • Use measured sustained throughput for time estimates; link speed alone excludes contention and protocol overhead.
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

Subnet CalculatorIP Range to CIDRCIDR MergerVLSM CalculatorLearn CIDR →

How calculations work and where the models stop →