Horsepower Calculator
Convert between horsepower, watts, and kilowatts.
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How It Works
Converts torque and RPM to horsepower using the mechanical formula: HP = Torque(ft·lb) × RPM ÷ 5252. The constant 5252 comes from converting RPM to radians per second and watts to horsepower.
Formula
1 HP = 745.7 WQuick Reference
Common calculations — results you can verify instantly.
300 ft-lb, 4000 RPM
300×4000/5252
228 HP
400 ft-lb, 5252 RPM
400×5252/5252
400 HP = 400 torque
1 HP to watts
1×745.7
745.7 watts
Tips & Shortcuts
1 horsepower = 746 watts = 550 ft·lb/second.
Peak torque and peak horsepower occur at different RPMs.
Horsepower is most useful at high RPM (highway speeds); torque matters for low-speed pulling.
Common Mistakes
Confusing metric HP (PS) with mechanical HP
1 metric HP (PS) = 0.9863 mechanical HP. European car specs often use PS.
Thinking more horsepower always means faster acceleration
Torque determines initial acceleration. HP determines top speed and sustained acceleration.
Frequently Asked Questions
1 mechanical horsepower = 745.7 watts. A 200 HP engine produces ~149 kW.
Torque is rotational force (what moves you from a stop). Horsepower is torque multiplied by speed (what keeps you moving fast).
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