Horsepower Calculator
Estimate engine horsepower from torque and RPM, or from quarter-mile trap speed.
Assumptions used in this calculation
- Trap speed method: The weight/trap-speed formula is a widely used approximation, not an exact dyno measurement.
About this calculator
Horsepower isn't printed on a spec sheet in every situation, sometimes you only have a torque reading at a specific RPM from a dyno pull, or just a quarter-mile time slip with a trap speed and know the car's weight. This calculator handles both cases: from torque and RPM it applies HP = (Torque × RPM) ÷ 5252, the standard conversion that makes torque and horsepower numerically equal at exactly 5,252 RPM; from vehicle weight and trap speed it applies the widely used estimate HP = Weight × (Trap speed ÷ 234)³. It's useful for enthusiasts reading a dyno sheet, drag racers estimating power from a time slip, or anyone trying to sanity-check a claimed horsepower figure. The trap-speed formula in particular involves a cube, tedious to compute reliably by hand, so this calculator gives an instant estimate you'd otherwise need a spreadsheet or lookup table for.
Worked example
300 lb-ft at 5252 RPM
Result: 300 hp
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