Advanced Route Summarization Tool

Calculator

Enter one IPv4 route per line using CIDR notation. Example: 10.10.0.0/24

IPv4 Routes

Accepted Input Rules

Use IPv4 only.
One route per line.
Use CIDR format.
Prefix must be 0 to 32.
Spaces around slash are allowed.

What This Tool Returns

Aggregate summary CIDR
Subnet and wildcard masks
Broadcast address
Covered address range
Route coverage validation
CSV and print-to-PDF export

Example Data Table

Input Route	Network Address	Broadcast Address	Addresses
192.168.8.0/24	192.168.8.0	192.168.8.255	256
192.168.9.0/24	192.168.9.0	192.168.9.255	256
192.168.10.0/24	192.168.10.0	192.168.10.255	256
192.168.11.0/24	192.168.11.0	192.168.11.255	256

Formula Used

Route summarization finds the smallest supernet covering every input route. First, convert each network and broadcast address into 32-bit binary values. Next, compare the lowest network address and highest broadcast address. The count of leading matching bits becomes the summary prefix length.

Summary Network = Lowest Address AND Summary Mask

Summary Mask = Prefix bits set to 1, remaining bits set to 0

Broadcast Address = Summary Network + 2^(32 − Prefix) − 1

Total Addresses = 2^(32 − Prefix)

Wildcard Mask = Inverse of Subnet Mask

How to Use This Calculator

Enter IPv4 routes, one per line, using CIDR notation.
Click Summarize Routes to calculate the aggregate prefix.
Review the returned summary CIDR, subnet mask, wildcard mask, and broadcast address.
Check the coverage table to confirm every entered route fits inside the summary.
Use the CSV button for spreadsheet export.
Use the PDF button to open a print-friendly report and save it as PDF.

FAQs

1. What does route summarization do?

It combines multiple contiguous or closely related IPv4 networks into one broader prefix. This reduces routing table size and simplifies route advertisement.

2. Does this tool support IPv6?

No. This version is built for IPv4 routes only. IPv6 summarization uses similar ideas, but the address format and bit handling differ.

3. Must the routes be contiguous?

Not strictly. The tool still finds the smallest covering supernet. However, noncontiguous inputs may produce a broader summary than expected.

4. Why can summarization create extra address space?

Because the smallest shared prefix may include addresses not present in the original list. This is normal when routes do not align perfectly.

5. What is the wildcard mask used for?

The wildcard mask is the inverse of the subnet mask. It is commonly used in ACLs, routing policies, and device matching rules.

6. Why does the tool show broadcast and range values?

These values help verify what the summary truly covers. They make it easier to see whether all route boundaries fit inside the aggregate block.

7. Can I export the results?

Yes. The page supports CSV export directly and offers a print-friendly layout that can be saved as PDF from your browser.

8. What happens if I enter invalid routes?

The tool validates each line. Invalid entries produce error messages, and summarization runs only after at least one valid IPv4 route is supplied.