VLAN ID Planner
Allocate 802.1Q VLAN IDs across sites in aligned blocks and check the plan fits the 4094 usable IDs.
About VLAN ID Planner
Rounding each site's allocation up to a power of two keeps VLAN ranges aligned, so a site's VLANs can be summarised in a trunk allowed-list or matched by a single mask instead of an arbitrary range. The planner then checks the total against the 4094 IDs 802.1Q actually gives you. VLAN IDs are a 12-bit field with no way to extend it, so a numbering scheme that is not aligned and bounded from day one turns into a renumbering project the first time you add a site.
Formula
VLAN ID
Each site gets the next power of two above its VLAN count so blocks stay bit-aligned; total = sites × block size, against the 4094 usable IDs.
- 4094
- 802.1Q usable VLAN IDs — 0 and 4095 are reserved by the standard
- block size
- 2^ceil(log2(VLANs per site))
- available
- 4094 minus the IDs you hold back for infrastructure
Worked example
With the default values below, VLAN ID Planner returns Total VLAN IDs Consumed of 384. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Sites to numberaccepts 1–500 sites
- 12 sites
- VLANs needed per siteaccepts 1–512 VLANs
- 20 VLANs
- IDs reserved for infrastructureaccepts 0–4,000 IDs
- 100 IDs
- First allocatable VLAN IDaccepts 1–4,094
- 101
Results
- Aligned Block per Site
- 32 IDs
- Total VLAN IDs Consumed
- 384
- Sites the ID Space Supports
- 124
- Last VLAN ID Used
- 484
- 802.1Q ID Space Used
- 9.38%
- Verdict
- Fits — 3610 IDs spare
Step by step
- 1Values used
- 2VLAN ID
- 3Total VLAN IDs Consumed= 384
- 4Aligned Block per Site= 32 IDs
- 5Sites the ID Space Supports= 124
- 6Last VLAN ID Used= 484
- 7802.1Q ID Space Used= 9.38
- 8Verdict= Fits — 3610 IDs spare
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is VLAN ID calculated?
Each site gets the next power of two above its VLAN count so blocks stay bit-aligned; total = sites × block size, against the 4094 usable IDs. Rounding each site's allocation up to a power of two keeps VLAN ranges aligned, so a site's VLANs can be summarised in a trunk allowed-list or matched by a single mask instead of an arbitrary range. The planner then checks the total against the 4094 IDs 802.1Q actually gives you.
Why does VLAN ID matter?
VLAN IDs are a 12-bit field with no way to extend it, so a numbering scheme that is not aligned and bounded from day one turns into a renumbering project the first time you add a site.
What values do I need to enter?
This calculator takes 4 inputs: Sites to number, VLANs needed per site, IDs reserved for infrastructure, First allocatable VLAN ID. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.
What happens when 4094 VLANs is not enough?
You move the scaling boundary above 802.1Q: QinQ (802.1ad) gives a second 12-bit tag, and VXLAN's 24-bit VNI gives roughly 16 million segments. Both keep VLAN IDs local to a switch or site rather than globally unique.