VLAN Planner

Plan VLAN subnets with VLSM allocation. Add departments with host counts and get optimized IP ranges.

Root Network

Network Address

Base IP address of your network.

CIDR

Departments

Engineering120 hosts · VLAN 10

HR25 hosts · VLAN 20

Guest WiFi50 hosts · VLAN 30

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VLSM Allocation

Departments

224

IPs Used

65,536

Total Capacity

0.3%

Used

Allocation Table

Department	VLAN	Needed	Usable	Network	Range	Broadcast	Mask
Engineering	10	120	126	10.0.0.0	10.0.0.1 — 10.0.0.126	10.0.0.127	/25
Guest WiFi	30	50	62	10.0.0.128	10.0.0.129 — 10.0.0.190	10.0.0.191	/26
HR	20	25	30	10.0.0.192	10.0.0.193 — 10.0.0.222	10.0.0.223	/27

Documentation

How It Works

The VLAN Planner uses VLSM (Variable Length Subnet Mask) to efficiently allocate IP blocks. It sorts departments by size (largest first) and assigns the smallest power-of-2 block that fits each department's host count plus network/broadcast overhead.

VLSM Algorithm

Step 1: Sort departments by host count (largest first)

Step 2: Calculate smallest /xx that fits hosts + 2

Step 3: Align to block boundary, assign IPs

Step 4: Repeat for each department sequentially

Last Updated: February 2026. IPv4 only.

Frequently Asked Questions