Supernet Calculator
Aggregate multiple contiguous networks into a single supernet with the smallest matching prefix.
About Supernet Calculator
Supernetting (route aggregation) combines multiple contiguous networks into one larger summary route by finding the longest common prefix between the first and last network addresses. The result is a single CIDR block that encompasses all the original networks, reducing routing table entries.
Formulas
Supernet prefix
prefix = number of common leading bits between first and last network
- common bits
- Count of identical leading bits across all networks
Networks aggregated
count = 2^(original_prefix - supernet_prefix)
- p_orig
- Original per-network prefix
- p_super
- Resulting supernet prefix
Worked example
With the default values below, Supernet Calculator returns Supernet (Summary Route) of 192.168.0.0/22. Change any input above and every figure here is recalculated in your browser.
Inputs used
- First Network Address
- 192.168.0.0
- Last Network Address
- 192.168.3.0
- Original Prefix Lengthaccepts 1–30
- 24
Results
- Supernet (Summary Route)
- 192.168.0.0/22
- Supernet Prefix
- /22
- Networks Aggregated
- 4
- Total Host Addresses
- 1,022
Step by step
- 1XOR addresses to find differing bits= 0.0.3.0
- 2Count common leading bits= 22
- 3Supernet prefix= /22
- 4Networks aggregated= 4
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
When should I use supernetting?
Supernetting is used to reduce routing table size by summarizing multiple contiguous routes into one aggregate route. It's essential for BGP route announcements and any scenario where routing table efficiency matters.
Do the networks need to be contiguous?
Yes — only contiguous, properly aligned networks can be accurately summarized into a single supernet without inadvertently including address space that isn't part of the original set.