VLSM Planner¶
Variable Length Subnet Masking allocates subnets of different sizes from a single parent block, minimising address waste.
How it works¶
- Enter the parent network (e.g.
10.0.0.0) and prefix length (e.g.24). - Add rows — one per subnet — with a name and the number of hosts needed.
- Click Calculate.
The planner sorts subnets largest-first, then greedily allocates the smallest power-of-2 block that fits each requirement from the remaining address space.
Result table columns¶
| Column | Description |
|---|---|
| Name | Label you entered |
| Hosts Needed | Your requested host count |
| Allocated Subnet | The CIDR block assigned |
| Usable | Usable host addresses in the block |
| Waste | Usable − Hosts Needed |
Summary bar¶
Below the table: total hosts requested, total allocated addresses, remaining addresses, and utilisation percentage.
Export¶
| Button | Output |
|---|---|
| Export CSV | Comma-separated values file |
| Export JSON | JSON array of row objects |
| Export XLSX | Excel workbook (via SheetJS) |
| Export ASCII | Plaintext tree diagram copied to clipboard |
Sessions¶
See VLSM Sessions to save and restore your planner inputs.