Electric Motor Torque & HP Calculator
Convert between electric motor horsepower, torque (lb-ft), and RPM for performance analysis and system matching.
What do you want to calculate?
Input Values
Motor Calculations
Horsepower, torque, and RPM are related by the formula: HP = (Torque × RPM) / 5252. This calculator converts between all three values.
- • 1 HP = 745.7 watts = 33,000 ft-lb/min
- • 1 lb-ft = 1.3558 N·m
- • Common speeds: 1800, 1200, 900 RPM
How to Use
- Select what you want to calculate (HP, Torque, or RPM)
- Enter the two known values
- Click Calculate to see all motor specifications
FAQ
What is the 5252 constant?
The constant 5252 comes from dividing 33,000 ft-lb/min (the definition of 1 HP) by 2π (radians per revolution). It's the RPM where horsepower and torque are numerically equal.
Why do motors have standard speeds?
AC motors run at synchronous speeds based on pole count and frequency. At 60 Hz: 2-pole = 3600 RPM, 4-pole = 1800 RPM, 6-pole = 1200 RPM. Actual speed is slightly less due to slip.
Torque vs horsepower—what matters more?
Torque determines starting force and low-speed performance. Horsepower (torque × speed) determines sustained work capacity. For conveyors and crushers, prioritize torque. For fans and pumps, prioritize HP.