Motor Shaft Torque, Horsepower, and Speed
The horsepower-speed-torque triangle T = 5252 x HP / RPM, solving either way.
Example
You enter
- Shaft speed (rpm) 1750
- Horsepower (blank to solve from torque) 10
You get
- Shaft torque 30.01 lb-ft
- Horsepower 10 HP
Checked against published worked examples from: WEG Electric Corp.
Details, formula, and sources
ScopeSupply horsepower to get shaft torque, or torque to get horsepower, for coupling, belt, gearbox, and VFD torque-limit selection. The nameplate and driven load govern the service-factor margin.
Formula or tableT = 5252 x HP / RPM (5252 = 33,000 ft-lb/min per HP divided by 2 pi, the rev/min-to-rad/s bridge); inverse HP = T x RPM / 5252. Supply exactly one of HP or torque; the tile solves for the other.
Source and editionFirst-principles rotational-power identity (power = torque x angular speed).
Free accessFirst-principles physics; no licensed source required.
What governsEstimate. AHJ and licensed professional govern.
API field namesrpm, hp, torque_lbft
- Mechanical horsepower horsepower here is mechanical shaft horsepower at the stated speedfirst-principles rotational power
- Service factor the nameplate and the driven load govern the service-factor margin; this is the rated-point torquemotor nameplate / driven load