Security cameras · power
PoE camera power budget calculator.
Add up camera watts and compare them with the switch PoE budget and the port standard.
Inputs
Power budget
Enter the numbers above.
How to work out a PoE camera power budget
Two limits apply: each port, and the whole switch. Each IEEE standard caps the power at the device. Per Wikipedia's Power over Ethernet table, the switch (PSE) can supply up to 15.4 W on 802.3af Type 1, 30 W on 802.3at Type 2, 60 W on 802.3bt Type 3 and 90 W on Type 4, of which 12.95 W, 25.5 W, 51 W and 71.3 W is available at the camera after cable loss. A camera must stay under the device figure for its port, and the sum across all ports must stay under the switch's total PoE budget.
Worked example. Eight 7 W cameras on an 802.3af switch with a 120 W budget draw 56 W. Keeping a 20 percent spare leaves 96 W, so there is 40 W spare, and up to 13 cameras of 7 W would fit. If the switch reserves the full 15.4 W per port, the worst case is 8 x 15.4 = 123.2 W, which would not fit the 96 W you want to use.
Some switches allocate by the device's power class and some by measured draw, so read the switch datasheet. Cold-weather heaters and IR lighting can raise a camera's draw above its typical figure; use the maximum from the datasheet.
Frequently asked questions
How many cameras can a 120 W PoE switch run?
With 7 W cameras and a 20 percent spare margin, 13 cameras (91 W) fit inside the 96 W you keep available. The result changes with the camera wattage and port standard.
What are the PoE power limits?
Wikipedia lists 15.4 W at the switch and 12.95 W at the device for 802.3af, 30 W and 25.5 W for 802.3at, 60 W and 51 W for 802.3bt Type 3, and 90 W and 71.3 W for Type 4.
Should I size by actual draw or by class maximum?
It depends on how the switch allocates power. The tool shows both so you can see the worst case if the switch reserves the port maximum per camera.
Can one camera exceed the port limit?
Yes, a high-power PTZ or heated camera can. The tool flags a camera whose draw is above the device-side limit for the chosen standard.
Sources
Checked
- Wikipedia, "Power over Ethernet", opened 8 October 2026. power table: 15.4 W / 12.95 W (Type 1), 30 W / 25.5 W (Type 2), 60 W / 51 W (Type 3), 90 W / 71.3 W (Type 4)
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Scope
Electrical planning aid, not an electrical or installation design. Follow the manufacturer datasheets and have a qualified installer check cabling and equipment. Camera watts, other loads and the spare margin are your inputs. Use datasheet maximums, not typical figures.