Electric Motors - Efficiency

Electrical motor efficiency is the ratio between shaft output power and electrical input power. This tool calculates motor efficiency based on input and output power, and displays NEMA Design B efficiency standards.

Calculator

Inputs

Shaft Output Power (W)

Electrical Input Power (W)

Shaft Output Power (Alternative) (hp)

Results

Motor Efficiency (from Watt)-- %

Motor Efficiency (from Horsepower)-- %

Copper Loss (example: R=1Ω, I=10A)-- W

Power (hp)	Minimum Nominal Efficiency (%)
1 - 4	78.8
5 - 9	84
10 - 19	85.5
20 - 49	88.5
50 - 99	90.2
100 - 124	91.7
> 125	92.4