Supernet Calculator
Aggregate multiple contiguous networks into a single supernet with the smallest matching prefix.
Inputs
Supernet (Summary Route)
192.168.0.0/22
Supernet Prefix
/22
Networks Aggregated
4
Total Host Addresses
1,022
Step by step
XOR addresses to find differing bits
192.168.0.0 XOR 192.168.3.0
= 0.0.3.0
Count common leading bits
Leading zeros in XOR result
= 22
Supernet prefix
Common bits = 22
= /22
Networks aggregated
2^(24 - 22)
= 4
How it works
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
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.