Horsepower Calculator
Calculate horsepower from torque and RPM, or convert between horsepower and other power units.
Result
Fill in the fields above, then press Calculate.
A horsepower calculator converts between horsepower, torque, and RPM, and translates between mechanical, electrical, and metric horsepower units.
Examples
Engine producing 200 lb-ft at 5000 RPM
HP = (200 x 5000) / 5252 = 190.4 HP = 142.0 kW.
1 HP electric motor
1 HP = 746 watts. A 2 HP motor draws approximately 1,492 watts at full load.
Frequently Asked Questions
What is the difference between HP and metric HP (PS)?
One mechanical (imperial) horsepower equals 550 ft-lbs/s or 746 watts. One metric horsepower (PS, from German Pferdestarke) equals 75 kgf-m/s or 735.5 watts. 1 HP = 1.01387 PS.
Where does 5252 come from?
The constant 5252 is derived from 33,000 ft-lbs/min (definition of 1 HP) divided by 2pi: 33,000 / (2 x 3.14159) = 5252. It converts torque (lb-ft) and RPM to horsepower.
Result
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Quick Tips
- •Horsepower and torque are always equal at 5,252 RPM — this is where the curves cross on a dyno chart.
- •Electric motors produce peak torque at 0 RPM, unlike combustion engines which need to rev up.