PoE budget calculator

Calculation and assumptions

Allocated W = sum(quantity × allocation W per port)
Minimum W = round up(allocated W × (1 + headroom / 100))

Worked example: six ports allocated 30 W and eight allocated 15.4 W total 303.2 W. Adding 20% gives 363.84 W, rounded up to 364 W, with 14 PoE ports required. A 370 W, 16-PoE-port switch passes those two totals; its per-port standards still need checking.

Full-class switch-side allowances

For reference, 802.3af supplies up to 15.4 W at the source but 12.95 W at the device; 802.3at is 30 W versus 25.5 W. A device-side number is not interchangeable with a switch-side allocation. Reference: Omada's PoE standards explanation.

IEEE PoE planning only, not passive PoE or AC/UPS sizing. The calculation runs locally in your browser. Your device schedule stays in your browser unless you choose to send an enquiry.

Switch ranges and selection guides

• D-Link switches and networking
• TP-Link and Omada networking
• Digisol networking
• Fortinet networking and security
• PoE budget explained
• PoE versus PoE+

PoE planning questions

How do I calculate a PoE switch power budget?

Multiply each device group's quantity by the power allocated at the switch port, add the groups, then add your chosen headroom. Check the switch's total PoE budget, PoE port count and each port's supported standard separately. A total that fits is not a compatibility approval.

Can I use a camera's typical power consumption?

Not as the switch allocation without checking the manufacturer's specification. Power reserved by the switch can exceed typical device consumption, and power delivered to the device is lower than power supplied at the port because of cable loss. Use the manufacturer's switch-side allocation or a suitable full-class allowance.

Is 20% headroom mandatory?

No. The example uses 20% as a planning assumption, not an IEEE requirement. Choose headroom for your project's growth and operating constraints. This calculator adds power headroom only; spare PoE ports are a separate check.