Horsepower to Torque Calculator

T (lb-ft) = 5252 × HP / RPM. The fundamental engine equation.

Inputs

Result

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How to use this calculator

  • Enter HP and RPM.
  • Read torque in lb-ft and N·m.

About this calculator

Horsepower and torque are mathematically linked: HP = T × RPM / 5252 (or T = 5252 × HP / RPM). The constant 5252 comes from 33,000 ft-lb/min = 1 HP, divided by 2π (radians per revolution). At 5252 RPM, HP = T numerically — that's why dyno graphs cross at 5252 RPM. Diesels make peak torque low (1500-3000 RPM); racing engines peak high (7000-9000 RPM). Modern turbos: peak torque from 1500-5000 RPM (flat torque curve).

Frequently asked

Why 5252?+
33,000 ft-lb/min per HP / (2π) = 5252.11. Ensures HP = T × RPM / 5252.
Why do dyno graphs cross at 5252 RPM?+
At RPM = 5252, HP and lb-ft are numerically equal. Always. Constant of the formulas.
HP for racing or torque for daily?+
Both matter. Daily driving feels torque (low-RPM acceleration). Top-end (highway passes, racing) wants HP at peak.
EV torque advantage?+
EVs deliver max torque from 0 RPM. Tesla Model 3 Performance: 471 lb-ft at 0 RPM. Gas cars need to rev to reach peak.
kW vs. HP vs. PS?+
kW = SI. HP = US/Imperial mech. PS (German Pferdestärke) ≈ HP but defined differently (75 kgf·m/s vs. 550 ft-lb/s). 1 PS = 0.9863 HP. Often confused.

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