PoE Standards Comparison

How to Use This Chart

Find your camera’s power draw (on its label or spec sheet), then read across the table to the standard whose Power at Device figure covers it with a little headroom. The common names map to IEEE designations that get mixed up: PoE is 802.3af, PoE+ is 802.3at, and PoE++ (also called 4PPoE) is 802.3bt, which comes in Type 3 and Type 4 power tiers.

Always size to the Power at Device column, not the switch output — the device gets less than the switch sends because power is lost in the cable. The standards are backward compatible, so a PoE+ or PoE++ switch safely powers an older 802.3af camera at the level it needs. Once you’ve picked a standard, confirm the switch’s total budget covers every camera with the PoE Budget Calculator.

When This Tool Is Most Useful

This comparison is most useful when you’re:

• Matching a switch or injector to a camera’s power requirement
• Deciding whether a camera with IR, a heater, or PTZ needs PoE+ or PoE++
• Checking that a new camera will work on an existing PoE switch
• Understanding why a switch’s rated watts differ from what the camera receives
• Citing exact PoE power and voltage figures for a plan or spec

Worked Example

Say you’re speccing three different cameras and want to know which PoE standard — and switch — each one needs. Read down the Power at Device column:

• A basic 4MP fixed dome draws about 5–7 W. That’s comfortably inside 802.3af (12.95 W at the device), so any standard PoE switch powers it.
• A bullet camera with strong IR and a winter heater can pull 12–15 W at night. That’s right at the edge of 802.3af, so you want 802.3at (PoE+, 25.5 W) for headroom — under-powering it is a common reason IR cameras brown out after dark.
• A PTZ dome that pans, tilts, and zooms can spike to 20–25 W when the motors and heater run together. That is at the ceiling of 802.3at (PoE+, 25.5 W at the device), so a large multi-sensor or high-power PTZ should go to 802.3bt (PoE++) for headroom.

Two rules make the choice: match the standard to the camera’s power-at-device number, not the switch’s output, and confirm the switch’s total budget covers every camera at once. A switch can be PoE+ on each port yet still run out of total watts across eight ports — the PoE Budget Calculator settles that, and the PoE Voltage Drop Calculator checks the run is short enough to actually deliver it.

Common Mistakes

• Reading the switch output instead of power-at-device. The camera always gets less than the switch sends, so size to the Power at Device column.
• Confusing per-port standard with total budget. A PoE+ switch can still be short on total watts across all ports; check the combined budget.
• Buying passive 24 V “PoE” gear. It isn’t an IEEE standard and can fail to power — or even damage — 802.3 devices. Keep passive and standard PoE separate.
• Under-powering IR, PTZ, or heated cameras. These spike at night or in cold and brown out on 802.3af. Use PoE+ or higher for them.
• Assuming more power is always better. A basic camera on a PoE++ port only draws what it needs, so pay for the standard your cameras actually require, not the biggest one.

Accuracy & Assumptions

The figures are the IEEE standards’ rated values. In the field, a few things shift what a device actually receives:

• Cable loss — long or thin runs deliver less than the rated power-at-device
• Total switch budget — per-port capability doesn’t guarantee every port powered at once
• Backward compatibility — a higher switch powers a lower device at the device’s level, not the switch’s maximum
• Passive / proprietary PoE — 24 V and other non-IEEE schemes don’t follow this table
• Type 3 vs Type 4 — 802.3bt has two power tiers, so check which your switch and camera support

Match the standard to the camera’s draw with headroom, confirm the total budget, and verify the run length before you buy.

Next Steps

Know the standard you need? Confirm your switch can power every camera with the PoE Budget Calculator, and check a long run still delivers the watts with the PoE Voltage Drop Calculator. Shopping for a switch? See the best PoE switches for security cameras, and for reach limits, how far you can run a PoE camera.

Related Resources

Related calculators & charts

• PoE Budget Calculator — confirm the total switch wattage covers your cameras
• PoE Voltage Drop Calculator — check the power reaching a camera on a long run
• NVR Storage Calculator — size the drive for the same system

Related guides

• Best PoE Switches for Security Cameras — the budget and features to look for
• How Far Can You Run a PoE Camera? — distance limits and how to go beyond them

Browse all free security camera & NVR tools.

Frequently Asked Questions

What are the different PoE standards?

The three IEEE PoE standards are 802.3af (standard PoE, about 15.4 W at the switch), 802.3at (PoE+, about 30 W), and 802.3bt (PoE++ or 4PPoE, up to 60 W or 90 W). Each newer standard delivers more power while staying backward compatible, so a PoE+ switch will still power an older 802.3af camera.

What is the difference between PoE, PoE+, and PoE++?

They differ mainly in power. PoE (802.3af) gives about 15.4 W at the switch, PoE+ (802.3at) about 30 W, and PoE++ (802.3bt) up to 60 W or 90 W. More power supports heaters, pan-tilt-zoom motors, and brighter infrared. Pick the standard that meets your camera wattage with headroom to spare.

Are 802.3af and 802.3at 24V or 48V?

Neither is 24 V. 24 V passive PoE is a separate, non-IEEE scheme and is incompatible with both. 802.3af (Type 1) PSE output is 44–57 V, nominally 48 V. 802.3at (Type 2, PoE+) PSE output is a narrower, higher-floor range of 50–57 V; that higher floor is part of why it can deliver more power without excessive cable loss.

Is Cat5e or Cat6 better for PoE?

Both carry PoE the full 100 meters, but Cat6 has slightly lower resistance and handles the higher current of PoE++ with less heat, making it the safer choice for high-power runs or bundled cables. For standard PoE and PoE+ over normal distances, good solid-copper Cat5e is perfectly fine.

Which PoE standard do I need for a security camera?

Most fixed cameras run on standard 802.3af, about 12.95 W at the device. Cameras with heaters, strong IR, or PTZ motors usually need 802.3at (PoE+, 25.5 W), and multi-sensor or high-power PTZ domes may need 802.3bt (PoE++). Check the camera rated draw and pick a switch that meets it with headroom.

Are PoE standards backward compatible?

Yes. IEEE PoE switches negotiate power with each device, so a PoE+ or PoE++ switch safely powers an older 802.3af camera at the lower level it needs. The camera never receives more than it requests, so mixing standards on one switch is fine as long as the total budget covers them all.

Why does the camera get fewer watts than the switch sends?

Some power is lost as heat in the cable between the switch and the camera, so the power at the device is always lower than the switch output, for example 15.4 W at an 802.3af switch but 12.95 W at the camera. Size to the power-at-device column, and expect a bit less on long runs.

What does 802.3af PoE mean?

802.3af is the original IEEE PoE standard. A compliant PSE (switch or injector) supplies up to 15.4 W at 44–57 V; the powered device receives about 12.95 W after cable loss. That is enough for basic fixed cameras and VoIP phones. Devices with heaters, PTZ motors, or strong IR need 802.3at or 802.3bt instead.

Is 802.3af PoE or PoE+?

802.3af is PoE. PoE+ is 802.3at; PoE++ (also called 4PPoE) is 802.3bt. 802.3af tops out around 12.95 W at the device; 802.3at reaches 25.5 W.

Is 802.3af compatible with 802.3at?

Yes. IEEE PoE switches negotiate power with each device, so an 802.3at (PoE+) switch or injector safely powers an 802.3af (PoE) device at the lower level it requests. The device never receives more than it needs. The reverse does not work: an 802.3af switch cannot deliver 802.3at-level power.

Last updated: September 2026