PoE (Power over Ethernet) Calculator
This tool checks if your PoE switch can power a given number of devices (e.g., IP cameras, access points) based on each device’s power draw and the switch’s total PoE budget. For more accurate planning, consider cable lengths, voltage drops, and real device startup/current peaks.
Switch & Device Power Inputs
Note: Typical PoE classes under 802.3af/at:
- PoE (802.3af): ~15.4 W max (12.95 W at device)
- PoE+ (802.3at): ~30 W max (25.5 W at device)
- PoE++ / 802.3bt Type 3 / Type 4: up to ~60/100 W
What is a Power over Ethernet (PoE) Calculator and How to Use It?
Introduction
Power over Ethernet (PoE) technology enables both power and data transmission over a single Ethernet cable, eliminating the need for separate power sources for network devices like IP cameras, Wi-Fi access points (APs), VoIP phones, and IoT devices. However, every PoE switch has a limited power budget, and exceeding this can lead to underpowered or non-functional devices.
A PoE Calculator is a simple yet essential tool that helps network engineers, IT administrators, and installers determine whether a PoE switch can sufficiently power all connected devices based on its total power budget and per-device power consumption.
Why Use a PoE Calculator?
- Prevents Power Overload – Ensures that the total power consumption does not exceed the switch’s PoE budget.
- Efficient Device Allocation – Helps determine how many devices can be supported by a single PoE switch.
- Optimized Network Planning – Assists in selecting the right PoE switch or deciding if additional power injectors are needed.
How a PoE Calculator Works
The calculator uses the following formula:
Where:
- PoE Switch Budget (in watts) is the maximum power the switch can provide.
- Power Consumption per Device (in watts) is the power needed for each connected device.
- Number of Devices is the total number of PoE devices you intend to connect.
How to Use the PoE Calculator
- Enter the total PoE budget of your switch (e.g., 370W, 720W).
- Enter the power requirement per device (e.g., 7W for VoIP phones, 15W for APs, 25W for cameras).
- Enter the number of devices you plan to connect.
- The calculator will determine if your PoE switch can handle all the devices and how much power remains.
Example Calculation
Scenario 1: Small Business Network
- PoE Switch Budget: 250W
- IP Cameras: 8 cameras, each requiring 15W
- Wi-Fi Access Points: 4 APs, each requiring 20W
Conclusion: ✅ The switch can handle the devices, and 50W remains available for additional devices.
PoE Power Classes and Standards
PoE operates under different IEEE standards, defining maximum power per device:
| PoE Type | Standard | Max Power per Port |
|---|---|---|
| PoE (802.3af) | 15.4W | Suitable for VoIP Phones, Basic APs |
| PoE+ (802.3at) | 30W | IP Cameras, High-power APs |
| PoE++ (802.3bt) | 60W – 90W | High-power devices (PTZ cameras, lighting) |
Always ensure your switch supports the required PoE type for your devices.
Final Thoughts
A PoE Calculator is an essential tool for network planning, preventing power shortages, and optimizing device distribution. By using this tool, IT professionals can maximize efficiency, avoid overloading PoE switches, and ensure stable power delivery to critical network components.