Unit of Work

Before learning about the unit of work we should first understand what work is. In general terms, work is basically defined as the measure of the displacement of an object or a point when a force is applied in a certain direction over some distance. Some of the common examples include riding a bike uphill or carrying something in the presence of earth’s gravity. In essence, work is nothing but a mechanical manifestation of energy. It is also represented by W.

To put it in a formula;



  • F is the force applied
  • D is the displacement
  • Let’s look at the work units below.

    SI Unit of Work

    Talking about the SI unit of work, it is joule (J) and is basically characterized by the work done by a force of one newton causing a displacement of one meter. Sometimes newton-metre (Nm) is also used for measuring work. However, as this unit is also used for torque it can get quite confusing. Thus, SI authority does not encourage anyone to use this unit.

    Following is the table of units and dimensional formula:

    SI unit N.m Joule
    CGS unit dyne-cm Erg
    Dimensional formula ML2T-2

    Other Units of Work

    Some of the commonly used work units also include erg in the cgs system, the horsepower-hour, the newton-metre, the foot-pound, the kilowatt-hour, the foot-poundal, and the litre-atmosphere. Notably, work has a similar physical dimension as heat, therefore, measurement units such as BTU, therm and Calorie, are also used for measuring work done.

    Converting The Units Of Work


    Equivalent Unit in Joules

    1 erg

    1.0E-7 J

    1 horsepower-hour

    2684519.54 J

    1 newton-metre

    1 J

    1 foot-pound

    1.35582 J

    1 kilowatt-hour


    1 BTU

    1055.06 J

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