What if the new prefix is smaller than the original?

If the new prefix length is smaller (a larger network), the formula produces a value less than 1, meaning the 'new' network is actually larger than the original — this calculator is meant for splitting into smaller subnets.

Subnet Count Calculator

Calculate how many smaller subnets of a given prefix length fit within a larger network block.

Inputs

Results

Number of Subnets: 8

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Formula

Subnet Count = 2^(New Prefix − Original Prefix)

Learn How This Works

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