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Subnetting Planner (VLSM)

Enter a base network, its CIDR prefix, and how many equal subnets you need to see the full breakdown of each resulting subnet.

How to use this tool

  1. 1Enter the base network address.
  2. 2Enter the base CIDR prefix.
  3. 3Enter how many equal subnets you need.
  4. 4See each subnet's network, broadcast, and usable range.

Frequently asked questions

What if I need unequal-sized subnets?+

This tool splits into equal-sized subnets — for unequal (VLSM) sizing, allocate your largest subnet requirements first, then re-run this tool on the remaining block.

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