UniFi Access Point PoE Budget and Switch Planning

Size a UniFi access point PoE budget by checking three things: the power standard required by each device, the number of compatible powered ports, and the switch’s shared wattage limit. A switch with spare Ethernet ports can still lack enough power for another AP.

This guide covers power planning using Ubiquiti’s published specifications and worked arithmetic. For radio features and AP selection, see U7 Pro vs U6 Pro compared. Once the AP model is chosen, bring its maximum power requirement back to the worksheet below.

Start with the switch’s total PoE budget

Do not multiply the per-port rating by the number of ports and treat the result as available power. Ubiquiti publishes a separate total PoE availability figure for each switch.

Switch	Ethernet ports	Powered ports	Total PoE availability
Lite 8 PoE	8 gigabit RJ45	4 PoE+	52 W
Lite 16 PoE	16 gigabit RJ45	8 PoE+	45 W
Pro 24 PoE	24 gigabit RJ45; 2 SFP+ uplinks	16 PoE+; 8 PoE++	400 W

These figures come from the individual switch specifications listed in Sources. The Lite 16 has twice the Ethernet ports of the Lite 8, yet seven fewer watts available for powered devices. Port count and power capacity therefore need separate lines in a purchase plan.

Treat each switch as its own budget. Spare power on a switch in another room does not help an AP connected to the overloaded one unless you change the cabling or its power source.

Match the power method before adding watts

Ubiquiti’s PoE reference distinguishes PoE, PoE+ and PoE++ support. Check the exact device and port specification, including the permitted input voltage and whether an older device requires passive PoE. A sufficient total wattage figure does not establish electrical compatibility.

For each AP, camera or phone, record:

• The exact model and its published maximum power consumption.
• The required PoE standard or supported power adapter.
• The switch and port that will supply it.
• Any accessories whose consumption is excluded from the base specification.
• Whether an injector supplies it independently of the switch.

An AP powered through an external injector still uses a data port, but its power does not come from that switch’s PoE budget. Include the injector in the equipment and power-outlet plan.

Build a power worksheet

Use maximum published consumption as the starting estimate rather than a quiet-period dashboard reading. The following inputs are hypothetical allowances to demonstrate the calculation; they are not specifications for named products.

Planned load	Quantity	Assumed maximum per device	Subtotal
Access points	2	15 W	30 W
Camera	1	8 W	8 W
Total device load	3		38 W

With those inputs, a 52 W budget leaves 14 W before cable losses, allocation behavior and expansion. A 45 W budget leaves 7 W. Adding one more device at the assumed 15 W raises the total to 53 W, exceeding both budgets.

That result is only an initial arithmetic screen. The switch must also have three compatible powered ports for the original plan, and each port must support its assigned device. A sum that fits the shared budget cannot make an incompatible port suitable.

Keep the worksheet per switch and label each cable destination. This makes a later camera addition a visible change to one budget instead of an unexplained loss of headroom.

Allow for delivery losses and expansion

The PoE standards distinguish power supplied at the switch from power delivered to the device. Cable losses are one reason these values differ. Do not assume a total equal to the published switch budget leaves enough margin at every cable endpoint.

There is no universal spare-power percentage that guarantees a design. Check the switch documentation and the devices’ allocation requirements, then add an explicit allowance for the equipment you expect to install. A proposed camera with a documented maximum is a more useful expansion line than an unexplained percentage.

The UniFi sizing planner provides an initial network estimate. Replace its assumed loads with the exact device specifications when reviewing a tight PoE budget.

Keep port speed separate from power

A suitable power standard does not guarantee the desired Ethernet speed. The switch table above lists gigabit RJ45 ports; the Pro 24 PoE’s faster SFP+ ports are uplinks, not faster powered RJ45 ports.

Record data speed and PoE capability in separate worksheet columns. This avoids choosing a switch that can power every AP but lacks the access-port speed specified in the plan. Uplink sizing and link aggregation are separate from the wattage calculation.

When devices restart or disappear during adoption

If several APs start dropping offline after another powered device is attached, check both the shared budget and the affected port’s power setting. Also inspect the Ethernet cable and power source; a repeated disconnect alone does not establish that the switch is overloaded.

The UniFi adoption failure guide separates power and link checks from DHCP, management-VLAN and controller-reachability problems. Work through those before resetting devices.

For the controller, gateway and switch roles around this worksheet, see the UniFi home network setup guide. Keep the completed port and power plan with the network configuration so that later additions can be checked against the same assumptions.