The Torque & Power Measurement

Click  para  leer la versión en español

Chassis dynamometer compact

Measuring the torque & power

You could find so many units to measure the power (and torque), because of this, this has to be brief. Starting with the Power:

Horsepower (hp) is the name of several units of measurement of power. The most common definitions equal between 735.5 and 750 watts.[1] Horsepower was originally defined to compare the output of steam engines with the power of draft horses in continuous operation. The unit was widely adopted to measure the output of piston engines, turbines, electric motors, and other machinery. The definition of the unit varied between geographical regions. Most countries now use the SI unit watt for measurement of power. With the implementation of the EU Directive 80/181/EEC on January 1, 2010, the use of horsepower in the EU is only permitted as supplementary unit.

1 hp ≈ 0.74569 kW ≈ 1.0138 ps

The kilowatt is equal to one thousand (103) watts. This unit is typically used to express the output power of engines and the power consumption of electric motors, tools, machines, and heaters. It is also a common unit used to express the electromagnetic power output of broadcast radio and television transmitters.

One kilowatt of power is approximately equal to 1.34 horsepower. A small electric heater with one heating element can use 1.0 kilowatt, which is equivalent to the power consumption of a household in the United States averaged over the entire year (8900 kW h divided by 365×24 hours).[5] (UK household consume about half this amount)[6] Also, kilowatts of light power can be measured in the output pulses of some lasers.

1 kW ≈ 1.341 hp ≈ 1.3596 ps

This unit (German: Pferdestärke = horse strength) is no longer a statutory unit, but is still commonly used in Europe, South America, Japan and India especially by the automotive and motorcycle industry. It was adopted throughout continental Europe with designations equivalent to the English horsepower, but mathematically different from the British unit.

DIN 66036 defines one horsepower as the power to raise a mass of 75 kilograms against the earth’s gravitational force over a distance of one metre in one second;[11] this is equivalent to 735.49875 W. Similar definitions were already common to the time of James Watt.

The PS was adopted by the Deutsches Institut für Normung (DIN) and then by the automotive industry throughout most of Europe, under varying names. In 1992, the PS was rendered obsolete by EEC directives, when it was replaced by the kilowatt as the official power measuring unit. It is still in use for commercial and advertising purposes, in addition to the kW rating, as many customers are still not familiar with the use of kilowatts for engines.

***For further reading about Wheel HorsePower or bhp, please click below:
whp, bhp, shp, ihp, nhp.***

1 ps ≈ 0.9863hp ≈ 0.73549 kW



1 hp 0.74569 kW 1.0138 ps -> to convert from HorsePower (hp) to kilowatts (kW) or PS you have to multiply the amount of hp by the conversion factor.


Converting 320 hp to kW -> 320 x 0.73569 238 kW

Converting 320 hp to ps -> 320 x 1.0138 324 ps


1 kW 1.341 hp 1.3596 ps -> to convert from kilowatt (kW) to horsepower (hp) or PS, you have to multiply the amount of kW by the conversion factor.


Converting 320 kW to hp -> 320 x 1.341 429 hp

Converting 320 kW to ps -> 320 x 1.3596 435 ps


1 ps 0.9863 hp 0.73549 kW -> to convert from ps to horsepower (hp) or kilowatt (kW), you have to multiply the amount of kW by the conversion factor.


Converting 320 ps to hp -> 320 x 0.9863 ≈ 315 hp

Converting 320 ps to kW -> 320 x 0.73549  235 kw


Measuring the torque:


Torque, moment or moment of force (see the terminology below), is the tendency of a force to rotate an object about an axis,[1]fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist to an object. Mathematically, torque is defined as the product of force and the lever-arm distance, which tends to produce rotation.

Loosely speaking, torque is a measure of the turning force on an object such as a bolt or a flywheel. For example, pushing or pulling the handle of a wrench connected to a nut or bolt produces a torque (turning force) that loosens or tightens the nut or bolt.

Usual units in the automotive world:

A newton metre is a unit of torque (also called “moment“) in the SI system. The symbolic form is Nm or N·m,[1] and sometimes hyphenated newton-metre. One newton metre is equal to the torque resulting from a force of one newton applied perpendicularly to a moment arm which is one metre long.

Conversion factors


A pound-foot (lb·ft or lbf·ft) is a unit of torque (a vector). One pound-foot is the torque created by one pound force acting at a perpendicular distance of one foot from a pivot point.

One pound-foot is exactly 1.3558179483314004 newton meters.[note 1]

The name “pound-foot”, intended to minimize confusion with the foot-pound as a unit of work, was apparently first proposed by British physicist Arthur Mason Worthington.[1] However, foot-pound (ft·lb or ft·lbf) is also sometimes used interchangeably with “pound-foot” to express torque.[2]


The kilogram-force (kgf or kgF), or kilopond (kp, from Latin pondus meaning weight), is a gravitational metric unit of force. It is equal to the magnitude of the force exerted by one kilogram of mass in a 9.80665 m/s2 gravitational field (standard gravity, a conventional value approximating the average magnitude of gravity on Earth).[1] Therefore one kilogram-force is by definition equal to 9.80665 N.[2][3] Similarly, a gram-force is 9.80665 mN, and a milligram-force is 9.80665 µN.

One kilogram-force is approximately 2.204622 pounds.



1 Nm ≈ 0.7375 lb-ft ≈ 0.1019 Kgm

Converting 1250 Nm to lb-ft: 1250 x 0.7375 ≈ 921 lb-ft.

Converting 1250 Nm to Kgm: 1250 x 0.1019 ≈ 127 Kgm.

1 lb-ft ≈ 1.355 Nm ≈ 0.1382 Kgm


Converting 1250 lb-ft to Nm: 1250 x 1.355 ≈ 1693 Nm.

Converting 1250 lb-ft to Kgm: 1250 x 0.1382 172 Kgm.

1 Kgm ≈ 9.806 Nm ≈ 7.233 lb-ft


Converting 1250 Kgm to Nm: 1250 x 9.806 12257 Nm.

Converting 1250 Kgm to lb-ft: 1250 x 7.233 9041 lb-ft.


If you want, you can use an online calculator:

main page:



Main page

Power & Torque:

**Both websites have different available options to convert, check them out.**

All what you need is to know the conversion factor. Basically, you have to multiply or divide, depending of the case and you will get your desired unit.


Posted on July 5, 2012, in General and tagged , , , , , , , , , , , , , , , , . Bookmark the permalink. 1 Comment.

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