How To Convert Torque Units

Torque is the turning effect of a force, equal to the force multiplied by the perpendicular distance from the pivot. The SI unit is the newton-metre, and it is the base for every other torque unit.

A foot-pound is the torque of one pound of force applied at one foot from the pivot. It equals about 1.3558179483 newton-metres and is the customary unit in the United States.

A kilogram-metre, sometimes written kilogram-force metre, is the torque of one kilogram of force at one metre. Because it uses the weight of a kilogram, it equals 9.80665 newton-metres.

An inch-pound is a twelfth of a foot-pound and equals about 0.112984829 newton-metres. It appears on small fasteners and precision instruments where foot-pounds are too coarse.

The converter expresses every unit as a size in newton-metres and converts by multiplying the value by the source factor and dividing by the target factor. That keeps every pair consistent.

The everyday conversion is newton-metres to foot-pounds. Multiply the newton-metres by 0.7375621, or divide by 1.3558179483, to get foot-pounds.

Going the other way, multiply foot-pounds by 1.3558179483 to get newton-metres. The factor is close to four thirds, which is why mechanics often approximate by multiplying by 1.356.

The kilogram-metre is not the same as the newton-metre even though both use a metre. The kilogram-metre includes the acceleration of gravity, so it is about 9.81 times larger.

The inch-pound is much smaller than the foot-pound, by a factor of twelve. A specification quoted in inch-pounds looks numerically larger for the same torque, so always check the unit.

The converter expresses every unit as a size in newton-metres and converts by multiplying the value by the source factor and dividing by the target factor. That keeps every pair consistent.

A frequent mistake is to confuse torque with energy. Both can be written as a force times a distance, but torque is a vector and energy is a scalar, and they are not interchangeable.

A second common error is to mix up the kilogram-metre and the newton-metre. Using 1 instead of 9.80665 for the kilogram-metre makes the answer about nine point eight times too small.

Every torque wrench is marked in one unit, so a specification in another must be converted before the wrench is set. A bolt calling for 100 newton-metres needs about 74 foot-pounds.

Automotive work mixes the two systems freely. An engine may be rated in newton-metres in Europe and pound-feet in the United States, so the same engine carries two different numbers.

Small fasteners are often specified in inch-pounds, where the numbers are large for a small torque. A specification of 100 inch-pounds is only about 8.3 foot-pounds.

The kilogram-metre appears in older European manuals and includes the acceleration of gravity, which is why it is about 9.81 newton-metres rather than one.

Torque and power are linked through angular speed, so a torque figure alone does not tell you how fast work is done. Converting torque and speed together gives the power in watts.

Bicycle and motorcycle manuals mix units, and a stem bolt might be specified in newton-metres while a wheel nut is in foot-pounds. Converting both to one unit before starting avoids reaching for the wrong setting.

Calibration certificates usually state the unit the wrench was tested in. If that differs from the specification, convert the specification rather than the certificate, so the reference stays untouched.

A torque-angle specification combines a torque value with a further rotation, so the unit matters for the first stage only. Converting that first figure correctly is what sets the fastener before the angle stage begins.

The calculator models the fixed relationships between the units and nothing more. It does not know the tolerance of your fastener or the accuracy of your wrench, so treat the output as exact arithmetic on the number you entered.