ElectraKit
Low-voltage and communications

PoE Power Budget Estimator

Compare a switch’s usable PoE output budget and per-port limits with powered-device maximum demand and a user-entered reserve.

Power over Ethernet inputs

Switch and device details

W

Use the total PoE output budget from the switch data sheet.

W

Use the limit for the selected port configuration.

devices
W

Use the worst-case power demand from the powered-device data sheet.

%

Optional planning margin applied to connected device demand.

PoE power budget screen

Planned switch power

237.6 W
Switch budget passes 132.4 W remains after the entered reserve.
Per-port limit passes Each device requests 18 W against an entered limit of 30 W per port.
Connected device demand216.0 W
Switch usable budget370.0 W
Maximum devices at this load and reserve18
Applied reserve10%
Budget estimate onlyThis does not identify PoE standards or power classes, verify negotiated power, cable losses, switch thermal limits, UPS runtime, network capacity, or powered-device compatibility. Check the exact switch port and device data sheets.

About this estimator

Enter the switch’s usable PoE power budget, the per-port output limit, the number of powered devices, each device’s maximum input power, and an optional reserve. The estimator compares total planned demand with the switch budget and checks the per-device value against the entered port limit.

Method and assumptions

Connected device demand equals device count multiplied by maximum power per device. Planned switch power equals connected device demand plus the selected reserve. The per-port check compares one device’s maximum input demand with the entered output limit.

The worksheet assumes every device has the same maximum demand. It does not calculate power class allocation, device startup behavior, cable loss, network capacity, or UPS runtime.

Interpret the result

A passing switch budget means the total planned demand is within the usable budget you entered. A passing per-port check means the device demand is within the entered per-port limit. Both checks depend on accurate product data and configuration-specific values.

FAQs

Which switch budget should I enter?

Enter the usable PoE output budget stated for the exact switch model and power-supply configuration. Do not use the switch’s total AC input rating.

Where should the device power value come from?

Use the powered-device manufacturer’s maximum input requirement for the selected operating mode, including attached accessories when they draw power from the device.

Does this check PoE classes or cable losses?

No. This worksheet uses the power values you enter. Verify standards negotiation, port allocation, cable losses, temperature limits, and device compatibility from the switch and device documentation.

Related tools

Low-Voltage Cable Voltage Drop EstimatorEstimate two-wire DC cable drop from cable data-sheet resistance.Battery Runtime CalculatorEstimate backup runtime from stored energy and load.Electrical Unit ConverterConvert common field electrical values.

Sources

  • Use the exact switch and power-supply data sheet for total PoE budget and per-port limits.
  • Use each powered device’s technical data sheet for maximum power demand and operating-mode requirements.