Planning
IPv4 route summarisation and CIDR aggregation calculator
Combine IPv4 subnets and address ranges into an exact set of CIDR blocks. Remove overlaps without adding addresses outside your input.
New to this tool? Start here.
Click an example below the form. Look at the result, then change one value to compare what happens.
- Route summarisation
- Replacing several network entries with fewer entries. Exact aggregation does not add addresses that were absent from the input.
- Supernet
- A larger block covering several networks. It can include gaps between them, so it differs from exact coverage.
01 / Input
Start with your data
Your data is processed in the browser. Sharing a result is your choice.
02 / Your result
A result you can understand.
Fill in the form or choose an example. You will see the values and how they were calculated.
02 / Your result
Step by step
How did we get here?
How to use it
Enter CIDR networks or IPv4 ranges. Exact aggregation preserves the address set. A common supernet may also include addresses outside that set.
A little network lab
Two routes written as one
Combine 192.168.0.0/24 and 192.168.1.0/24 without adding addresses from outside them. Both adjacency and block alignment matter.
Two blocks of 256 addresses give 512 addresses. That size corresponds to a /23.
A /23 here starts at an even third octet. Block 192.168.0.0/23 covers .0.0–.1.255, exactly the two input networks.
Check the full range, not just the shorter notation. Exact summarisation preserves the addresses in the input list.
Your turn
Can 192.168.4.0/24 and 192.168.5.0/24 be combined?
Show answer and explanation
Yes: exactly into 192.168.4.0/23. The start is aligned and the two blocks are adjacent and equally sized.
Official documents
Standards & sources
Sources checked:
The date refers to checking the listed documents and registries, not endorsement by their authors. Calculation assumptions and limits appear with the result. How we prepare the material.