Convert torque specs to horsepower
An engine quote gives lb-ft at RPM — the same curve in horsepower is one multiplication away.
Tools used in this guide
The job
Torque twists; power is torque times speed. Specs sheets mix them — a truck brags lb-ft, a sports car brags hp. Converting puts both on one axis.
Torque and RPM
Enter torque in lb-ft or Nm and the engine speed. Read hp, kW, and metric PS. The classic constant: hp = lb-ft × RPM ÷ 5252.
Worked example
400 lb-ft at 5,252 RPM is exactly 400 hp — the crossover where the two curves always meet. The same 400 lb-ft at 3,000 RPM is ~229 hp, which is why diesels feel strong yet post modest hp numbers.
Where it stops
This is crankshaft math — wheel horsepower runs lower through drivetrain losses (roughly 10–20 %). It converts one point; mapping a full power band means repeating it per RPM.