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Glossary Science & Engineering

Horsepower

Horsepower is a unit of power; one mechanical horsepower is 33,000 foot-pounds of work per minute, about 745.7 watts.

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In more detail

Engine power follows from torque and speed: hp = torque (lb-ft) × rpm / 5252, so 300 lb-ft at 5,000 rpm is 286 hp. Drag-strip trap speed also gives an estimate: weight × (mph / 234)³.

Try these tools

Horsepower Calculator

Estimate engine horsepower two ways — from quarter-mile trap speed and vehicle weight, or from torque and engine RPM.

See also

  • Glossary Kilowatt-hour (kWh)
    A kilowatt-hour is the energy used by a 1,000-watt device running for one hour, the unit on electricity bills.
  • Cheat sheet Vehicle Formulas Cheat Sheet
    Fuel cost, mpg and L/100 km, tire diameter and speedometer error, horsepower from torque or trap speed and EV charging cost.
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