Calculator Input
Example Data Table
| Scenario | Input Blocks | Smallest Summary | Exact Summary Set | Comment |
|---|---|---|---|---|
| Contiguous /24 blocks | 192.168.0.0/24 to 192.168.3.0/24 | 192.168.0.0/22 | 192.168.0.0/22 | Perfect exact aggregation into one route. |
| Two adjacent /25 blocks | 10.10.0.0/25 and 10.10.0.128/25 | 10.10.0.0/24 | 10.10.0.0/24 | Two equal halves merge cleanly. |
| Noncontiguous ranges | 172.16.0.0/24 and 172.16.2.0/24 | 172.16.0.0/22 | 172.16.0.0/24, 172.16.2.0/24 | Single summary covers an unused gap. |
Formula Used
Network Start = IP Address AND Subnet Mask
Total Addresses = 2(32 − Prefix Length)
Shared Prefix Length = Common leading bits between lowest start and highest end
Mask = Prefix bits set to 1, Wildcard = Inverse of mask
Efficiency % = (Exact entered addresses ÷ Smallest summary addresses) × 100
This calculator also builds an exact minimal summary set by decomposing merged address ranges into the fewest aligned CIDR blocks.
How to Use This Calculator
- Enter IPv4 CIDR blocks, one per line or separated by commas.
- Add an optional report label for exported files.
- Choose whether to show a single summary route, the exact summary set, or both.
- Decide if you want binary boundary details included.
- Press Calculate Supernet to place the result below the header and above the form.
- Review normalized inputs, summary metrics, and route reduction guidance.
- Use Download CSV for spreadsheets and Download PDF for a portable report.
Frequently Asked Questions
1. What is supernetting?
Supernetting combines multiple contiguous networks into fewer summary routes. It reduces routing table size, simplifies advertisements, and can improve routing efficiency when address blocks are aligned properly.
2. What is the difference between a supernet and an exact summary set?
A single supernet is the smallest one-route summary covering all entered ranges. An exact summary set uses one or more routes to match only the actual entered coverage, without including unused gaps.
3. Why does the calculator normalize some blocks?
If a host address is entered with a prefix, the tool converts it to the proper network boundary. That ensures range calculations, masks, and summaries reflect valid routed networks.
4. Why can the smallest summary include extra addresses?
When entered ranges are separated by gaps or do not align to one clean power-of-two block, the smallest single summary must cover unused addresses to include every entered network.
5. Does this calculator support IPv6?
No. This version is focused on IPv4 CIDR supernetting. The validation, binary view, masks, and wildcard logic are designed specifically for 32-bit IPv4 addressing.
6. What does coverage efficiency mean?
Coverage efficiency compares the exact entered address total with the address count inside the smallest single summary. Lower efficiency means more extra space is being advertised.
7. When should I prefer the exact summary set?
Use the exact summary set when you want precise route advertisement, especially when gaps exist. It avoids claiming unused ranges that could cause policy, security, or operational confusion.
8. Can overlapping or duplicate blocks be entered?
Yes. The calculator merges overlaps and adjacency before building results. That helps reveal the real unique address coverage and prevents duplicated ranges from inflating totals.