Power tools torque

Torque is a force that produces or tends to produce rotation or torsion.

Speaking in technically words torque is a force that causes something to spin around a central point such as an axle.

Referring to the rotating axle, torque, also called rotary force, is the product of the force multiplied by the length of the lever arm.

The formula is:

  • M = F x I


  • M is the torque measured in "newton-metre" (Nm)
  • F is a force measured in "newton" (N)
  • I is the length of the lever arm measured in "metre" (m)

Useful formula for relationship between torque and power:

torque formula


  • Power is measured in "kilowatt" (kW)
  • Torque is measured in "newton-metre" (Nm)
  • Rotational speed in measured in "revolutions per minute" (rpm)
  • 6,000 comes from 60 seconds per minute times 1000 watts per kilowatt

Some people (e.g. American automotive engineers) use horsepower (imperial mechanical) for power, foot-pounds (lbf·ft) for torque and rpm (revolutions per minute) for angular speed. This results in the formula changing to: torque formula This conversion factor is approximate because the transcendental number p appears in it.