CIDR Split Calculator
Split one IPv4 CIDR block into equal, aligned child networks.
Subdivide one CIDR into equal children
Increasing an IPv4 prefix borrows host bits to create equal smaller networks. This calculator normalizes the parent address to its true network boundary, verifies that the child prefix is longer, calculates the child block size, and enumerates every aligned child network in ascending order. It uses exact integer arithmetic for all 32 address bits.
The default /24 split at /26 returns four networks beginning at 192.168.1.0, .64, .128, and .192. Each child contains 64 total addresses and together they cover the parent exactly without overlap or gaps. A child prefix equal to or shorter than the parent is rejected because it would not be a subdivision.
Prefix growth and output limits
The page lists at most 1024 children in one result so a very large split does not freeze the browser or produce an unusable wall of text. That limit does not change the subnet math. Calculation remains in your browser. Consider route-table size, VLAN design, reserved addresses, and growth requirements rather than selecting a prefix solely because it divides evenly.
Frequently Asked Questions
How many children does a longer prefix create?
The count is two raised to the difference between child and parent prefix lengths.
What if the entered parent address is not the network address?
The calculator masks it to the true parent network before generating children.
Why is output limited to 1024 networks?
The limit keeps the interactive result usable; the underlying prefix calculation remains exact.
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