Before installing a PoE switch, one question always comes up: will it be able to power all my devices? This is the issue of the PoE budget. Here is a simple method to calculate it, typical power consumptions to know, and a free calculator to speed things up.
What is a switch's PoE budget?
The PoE budget is the total electrical power (in watts) that a switch can simultaneously supply across all its ports. For example, a 48-port switch might have a budget of 370 W. If the total power required by your devices exceeds this budget, some ports will stop supplying power.
Calculation method
The calculation involves three steps:
- List your PoE devices and their power consumption in watts.
- Add these power values to get the total requirement.
- Compare this total to the switch’s PoE budget, keeping a margin of about 20%.
In other words: total power = sum (each device’s consumption × quantity). The switch is suitable as long as this power stays below its PoE budget.
Typical power consumption of PoE devices
| Device | Indicative consumption |
|---|---|
| IP Phone | ~7 W |
| Fixed IP Camera | ~8 W |
| Motorized IP Camera (PTZ) | ~25 W |
| Wi-Fi Access Point (AP) | ~15 W |
| Wi-Fi 6 / 6E Access Point | ~25 W |
| Outdoor Access Point | ~30 W |
Automatically calculate your PoE budget
To avoid manual calculations, use our free PoE budget calculator: enter your devices and your switch’s budget, and it will immediately tell you if the setup works, including the remaining margin.
PoE standards: 802.3af, at, and bt
The standard determines the maximum power per port: 802.3af (PoE) provides 15.4 W, 802.3at (PoE+) 30 W, and 802.3bt (PoE++) up to 60 W (Type 3) or 100 W (Type 4). On the device side, the available power is slightly lower due to cable losses.
FAQ
What happens if I exceed the PoE budget?
The switch stops powering some ports (usually the lower priority ones). It’s better to plan a margin.
Are all ports on a PoE switch powered at the same time?
Yes, but within the overall budget limit. A switch may have 48 PoE ports but a budget that does not allow all to be powered at full capacity simultaneously.
Where can I find my switch’s PoE budget?
It is indicated in the manufacturer’s datasheet, in watts (total PoE power or “PoE power budget”).
To choose the right model, browse our used PoE and PoE+ switches and all our network switches, then deepen your knowledge with our PoE and PoE+ guide.