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VLSM Subnet Planner

Allocate non-overlapping LAN subnets from a parent network using required host counts. Work locally without uploading network information.

Runs entirely on your deviceNo uploads, accounts, cookies, or personal tracking.

Allocate LAN subnets

Local processing · no input storage

Network tools
Use a network boundary, not a host address.
One name and positive host count per line. No header row.

Allocates largest first, reserving network and broadcast addresses for every LAN. Insufficient capacity blocks the whole allocation.

Text lists: up to 500 non-empty lines and 256 KiB per field. Tabular results: up to 5,000 rows.

Enter your data, then select allocate lan subnets.
1. Add your data

Enter your network data or load the worked example.

2. Choose the result

Allocate LAN subnets and review the result and assumptions.

3. Save it locally

Copy the result or download it for your engineering workflow.

About this tool

Use VLSM Subnet Planner without an upload

Allocate non-overlapping LAN subnets from a parent network using required host counts. Work locally without uploading network information.

The operation runs in the current browser tab. Tool input is not included in aggregate analytics, and the standalone download makes no analytics requests.

Network toolsDeveloper tools