Engine Horsepower Calculator
Estimate engine horsepower from torque and RPM using the standard HP formula.
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How It Works
HP = Torque (ft-lb) x RPM / 5252. Constant 5252 converts units. At 5252 RPM torque and HP curves always cross.
Formula
HP = (Torque x RPM) / 5252Quick Reference
Common calculations — results you can verify instantly.
200 ft-lb, 5000 RPM
200×5000/5252
190 HP
500 ft-lb, 4000 RPM
500×4000/5252
381 HP
Torque = HP at 5252 RPM
Always
Curves always cross here
Tips & Shortcuts
Torque and HP are numerically equal at exactly 5252 RPM.
Wheel HP is 10-20% less than engine HP due to drivetrain losses.
Common Mistakes
Confusing SAE and metric HP
1 PS metric = 0.986 SAE HP. Nearly identical.
Equating engine HP with wheel HP
Drivetrain loses 10-20% before reaching wheels.
Frequently Asked Questions
74,570 watts = 74.6 kW.
Torque accelerates from rest. HP maintains speed at velocity.
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