Networking

CIDR Merger

Combine overlapping or aligned adjacent CIDR blocks without adding addresses.

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.

CIDR blocks, one per linePut each entry on its own line, following the example format.

02Your result

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

A quick guide

How to use this tool

Check the example and the unit beside each input.
Enter your values and choose Calculate.
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

A shorter output list describes the same address space. Adjacent blocks only merge when the larger block is correctly aligned.

Use in day-to-day IT work

Prepare an exact address summary for a firewall object or routing review.

Checks before applying the result

Check every resulting range against the original blocks; an exact merge must not authorise or advertise extra addresses.
A route summary also needs a valid forwarding and failure plan; mathematical coverage alone does not establish reachability.

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

How calculations work and where the models stop →