PoE Power Budget Calculator

Planning cameras, access points and other Power-over-Ethernet gear? Enter your switch's PoE budget, list what you're plugging in, and see your total draw, remaining headroom, and whether you're about to overload the switch — based on the IEEE 802.3 PoE standards. Free, no sign-up, all in your browser.

Your switch

Use the total PoE power budget from your switch's spec sheet (often well below the sum of all ports — e.g. an 8-port switch might list 60–65 W total).

Your PoE devices

Pick a PoE type for the per-device draw, or choose "Custom" and enter the manufacturer's max wattage. Figures are the power reserved from the switch (PSE-side) under each standard.

DevicePoE typeQty

PoE power questions, answered

What's the difference between port power and the switch's total budget?

Each port can deliver up to its PoE class limit, but the switch has a single shared power budget for all ports combined — and it's usually less than every port running at maximum. A switch with eight 30 W-capable ports might only have a 65 W total budget, so you can't run eight power-hungry devices at once. Always size against the total budget, which is the number this tool uses.

How much power does each PoE type provide?

Under the IEEE 802.3 standards, the switch (PSE) side reserves roughly: 15.4 W for 802.3af (Type 1 / standard PoE), 30 W for 802.3at (Type 2 / PoE+), 60 W for 802.3bt Type 3 (PoE++), and up to about 100 W for 802.3bt Type 4. The device actually receives a little less after cable loss — which is exactly why budgeting matters.

How much headroom should I leave?

Leaving around 10–20% spare is sensible. It covers power lost over long cable runs, devices that briefly draw more than their idle figure (PTZ cameras panning, APs under heavy load), and room to add a device later without re-planning. This calculator warns you once you cross about 90% of the budget.

Does cable length affect PoE power?

Yes. Power is lost as heat over the copper, so a device at the end of a long run receives less than it would on a short patch lead. The standards account for this by reserving more at the switch than the device needs, but very long runs (toward the 100 m limit) with thin cable make it worse — another reason to keep some budget in reserve.