Supernet Calculator
Use this supernet calculator to find the smallest covering IPv4 CIDR route for a list of subnets and see whether the summary covers extra addresses.
Calculator
How to use this calculator
Enter the planning values that match your network, storage, or cloud scenario. Use realistic production assumptions when sizing anything that affects availability, performance, or cost.
Formula or calculation method
The calculator finds the lowest network address and highest broadcast address, compares their common leading bits, then returns the smallest CIDR block that covers the entire span.
Worked example
Four adjacent /24 networks from 10.10.0.0/24 through 10.10.3.0/24 summarize cleanly as 10.10.0.0/22.
Practical planning tips
- Route summarization.
- Firewall documentation.
- IPAM cleanup and planning.
Common mistakes to avoid
- Summarizing non-contiguous networks without noticing extra coverage.
- Forgetting that route summaries can include unused addresses.
- Using a summary route without checking policy boundaries.
Frequently asked questions
Can a summary cover extra networks?
Yes. The result is the smallest covering route, which may include extra addresses if inputs are not perfectly adjacent.
Does this validate live routing?
No. It is a planning calculator only.