PoE Power Budget Calculator

Calculate your Power over Ethernet power budget by adding devices and selecting your PoE switch. Instantly see total power draw versus available budget, identify overload risks, and plan your network infrastructure — all calculated locally in your browser.

What Is Power over Ethernet (PoE)?

Power over Ethernet delivers both data and electrical power over standard Ethernet cables, eliminating the need for separate power supplies for devices like IP cameras, WiFi access points, and VoIP phones. PoE is defined by IEEE 802.3af, 802.3at, and 802.3bt standards, each offering increasing power levels.

Understanding your PoE power budget is critical when planning network infrastructure. If your total device power draw exceeds the switch's PoE budget, some ports will be de-prioritized and devices may lose power. Use this calculator alongside our Network Switch Calculator to plan both port count and power capacity.

PoE Standards Comparison

The IEEE has released several PoE standards, each increasing the maximum per-port and total switch power. When selecting a switch, consider which standard your devices require — especially power-hungry smart home devices and 4K PTZ cameras:

Cable Requirements for PoE

PoE performance depends heavily on your Ethernet cable quality and length. Higher power standards require better cables to minimize heat and voltage drop:

Use our Cable Length Calculator to estimate runs and account for voltage drop over distance. Longer cable runs reduce the power available at the device end.

Pro Tip: Always plan for 20-30% headroom in your PoE budget. Devices often draw more power during startup (inrush current) or peak operation. A WiFi AP rated at 15W typical may spike to 25W during heavy client load. If you're near the budget limit, consider upgrading to the next switch tier rather than running at capacity.

Common PoE Device Power Consumption

Here are typical power draws for common PoE-powered devices you'll find on a modern network, including smart home installations:

PoE Power Budget Planning Tips

When designing a PoE network for a home or small office, follow these best practices:

• Inventory all devices — List every PoE device and its maximum wattage. Use the calculator above to total them up.
• Account for growth — Plan for 30-50% more capacity than current needs. Adding IoT smart home devices later shouldn't require a switch replacement.
• Check per-port limits — A switch with 370W total budget may still limit individual ports to 15.4W if it's 802.3af only.
• Consider cable length — Longer runs reduce delivered power. Our Cable Length Calculator helps plan runs.
• Use managed switches — They allow PoE port prioritization and per-port power limits. See our Network Switch Calculator for sizing.
• Separate IoT networks — Consider a dedicated PoE switch for IoT devices on an isolated network segment.

Video: Power over Ethernet Explained

Related Guides

• Network Switch Calculator
• Bandwidth Calculator
• Cable Length Calculator
• Cat5e vs Cat6 Ethernet
• Cat6 vs Cat6a Ethernet
• Smart Home Router Requirements
• How to Separate IoT Devices
• UPS Runtime Calculator

Frequently Asked Questions

Can I mix PoE and non-PoE devices on the same switch?

Yes. PoE switches detect whether a connected device needs power before delivering it. Non-PoE devices connected to a PoE port will operate normally using only the data connection — no power is sent unless the device requests it through the PoE handshake.

What happens if I exceed my PoE budget?

Most managed switches use a priority system. Lower-priority ports will have PoE disabled to stay within the budget. Unmanaged switches may cycle ports or refuse to power new devices. This is why planning with headroom is essential.

Does PoE reduce my network speed?

No. PoE uses separate wire pairs (in 802.3af/at) or phantom power (802.3bt) that doesn't interfere with data transmission. You'll get the full speed your cable and switch support — 1Gbps, 2.5Gbps, or 10Gbps depending on your cable category.

Can I use PoE over long cable runs?

Standard Ethernet limits cable runs to 100 meters. With PoE, longer runs also mean more voltage drop, reducing delivered power. At 100m with Cat5e, a device may receive only 12W from a 15.4W source. Use Cat6a cable and PoE extenders for longer runs.

Do I need a special cable for PoE?

Standard Cat5e or better Ethernet cables work with PoE. However, Cat6 and Cat6a have lower resistance and are recommended for 802.3bt deployments and longer runs. Avoid CCA (Copper Clad Aluminum) cables — they have higher resistance and can overheat with PoE.

What is a PoE injector vs a PoE switch?

A PoE injector adds power to a single Ethernet run — useful when you have a non-PoE switch but need to power one or two devices. A PoE switch has power built into every port. For more than 2-3 PoE devices, a dedicated PoE switch is more cost-effective and easier to manage.

Can PoE damage non-PoE devices?

No. The PoE handshake protocol (classification) detects whether a device supports PoE before delivering power. If no valid PoE signature is detected, no power is sent. This makes it safe to plug any Ethernet device into a PoE port.

About Tommy N.

Tommy is the founder of RouterHax and a network engineer with 10+ years of experience in home and enterprise networking. He specializes in router configuration, WiFi optimization, and network security. When not writing guides, he's testing the latest mesh WiFi systems and helping readers troubleshoot their home networks.