Determine the mechanical horsepower produced by a rotating shaft given its torque and speed.
Mechanical Data
Results
Enter torque and speed to calculate horsepower
About this calculator
Overview
Horsepower is a fundamental unit of power. For rotating systems like electric motors or internal combustion engines, horsepower is a function of how much twisting force (torque) is being produced and how fast the shaft is spinning (RPM).
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Pro Tips
This formula requires torque to be in pound-feet (lb-ft).
The value 5252 is a conversion constant that accounts for the units of work (33,000 ft-lb/min) and rotational geometry (2π).
Because of the constant, an engine's torque and horsepower values are always equal at exactly 5252 RPM.
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Fun Facts
"While James Watt named the unit after a horse, a real horse can actually peak at about 15 horsepower for short bursts."
"The average healthy human can sustain about 0.1 horsepower for a long period."
"In the metric system, horsepower is often replaced by Kilowatts (kW). 1 HP ≈ 0.7457 kW."
