Engine Torque Calculator

Enter the horsepower and engine speed in RPM to calculate the torque of the motor.

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How to Calculate Engine Torque

Torque is the twisting force that causes rotation. In a gasoline or diesel engine, torque is the rotational force exerted by the crankshaft as a result of the combustion of the fuel-air mixture. Torque is a measure of the ability of a motor to perform work or move the vehicle forward.

Torque is typically measured in pound-feet (lb-ft) and newton-meters (Nm) in metric markets. To convert, one newton-meter is equal to 0.738 lb-ft.

Torque in lb-ft can be calculated using the angular velocity of the motor in revolutions per minute (RPM) and the power in horsepower. Try our engine horsepower calculator to find the power output of your motor.

The following formula can be used to calculate engine torque:

torque = (horsepower × 5,252) ÷ rpm

In this formula, 5,252 is the RPM at which horsepower and torque cross over on a graph showing the values at various RPM, assuming that the scales on both axes are identical.

Scottish engineer James Watt came up with the 5,252 number when developing his horsepower (HP) formula. It can be used for calculating torque using Imperial units (HP and lb-ft). If you are using metric units (Kw and Nm), it is necessary to use 9,549 in the formula instead of 5,252.

For example, let’s calculate the torque of an engine with 350 horsepower at 5,000 RPM.

torque = (350 × 5,252) ÷ 5,000
torque = 1,838,200 ÷ 5,000
torque = 367.64 lb-ft