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# VLSM subnet planner

Allocate unequal subnets from one IPv4 base, largest-first, with every sizing decision shown as a step and failures named per subnet.
workerless environment, same engine, this tab · up to 64 subnetsPlanClearSubnet 1 nameSubnet 1 hosts▲▼Subnet 2 nameSubnet 2 hosts▲▼Subnet 3 nameSubnet 3 hosts▲▼Subnet 4 nameSubnet 4 hosts▲▼Request listLoad into grid

Set the base and rows, then press Plan.

- Deterministic largest-first (classic VLSM): same inputs, same plan, every time. Equal sizes keep entry order. It is a teaching/planning layout, not a claim of optimality.
- "Usable hosts" is the IPv4 convention (network + broadcast reserved; RFC 3021 /31 and /32 exact). The same rule the subnet calculator prints.
- A request the base cannot satisfy is a named failure on its row: the plan never silently drops or shrinks it.
- Caps: 64 subnet rows per plan. Bulk tables run in the network family worker so planning never blocks the page.
Paste, drop, or type to begin. Everything stays on this device.

## More network tools

- [Subnet split & aggregate](/network/subnet-split)
- [IPv4 subnet calculator](/network/ipv4-subnet)
[All network tools](/network)

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Canonical HTML: https://nutter.tools/network/vlsm/
Markdown version: https://nutter.tools/network/vlsm/index.md
Plain-text version: https://nutter.tools/network/vlsm/index.txt
Agent index: https://nutter.tools/llms.txt