Subnet splitter

Split an IPv4 or IPv6 network by a longer prefix. Very large results use a bounded preview.

172.96.192.0/18 → /22

16 subnets

Subnets: 16
Addresses per subnet: 1,024
Last subnet: 172.96.252.0/22

Complete subnet listCIDRs: 16

172.96.192.0/22172.96.196.0/22172.96.200.0/22172.96.204.0/22172.96.208.0/22172.96.212.0/22172.96.216.0/22172.96.220.0/22172.96.224.0/22172.96.228.0/22172.96.232.0/22172.96.236.0/22172.96.240.0/22172.96.244.0/22172.96.248.0/22172.96.252.0/22

Divide a network into equal subnets

Enter a source CIDR and a new prefix length to calculate subnet counts, addresses per subnet and boundaries. Both IPv4 and IPv6 are supported.

Two examples, explainedCalculated examples

192.168.1.0/24 → /264 subnets

Addresses per subnet: 64
Resulting blocks: 192.168.1.0/26192.168.1.64/26192.168.1.128/26192.168.1.192/26

192.168.1.0/24 → /252 subnets

Addresses per subnet: 128
Resulting blocks: 192.168.1.0/25192.168.1.128/25

Same coverageThe subnets do not overlap and together cover the original network exactly.

Common questions

Does splitting change the total address count?

No. It partitions the same block into non-overlapping subnets that together cover the original range.

Can I allocate subnets of different sizes here?

This page splits using one new prefix length. For VLSM, calculate each required block separately and check its alignment.

Why must the new prefix be longer?

Each added prefix bit doubles the subnet count and halves addresses per subnet. A shorter prefix would enlarge the network rather than split it.

What if both prefixes are identical?

The result is one subnet: the normalized original network. The address count stays the same and no duplicate networks are created.

Why does the list stop at 256?

Large splits preview the first 256 subnets to keep the page usable. The total and final subnet are shown separately; the preview is not the complete list.

Can I allocate every address in a subnet?

Not necessarily. This is the total address count. IPv4 network and broadcast addresses, plus provider reservations, can reduce the allocatable count.