Horsepower vs. Joule — What's the Difference?

Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower.

The joule ( jowl, jool; symbol: J) is a derived unit of energy in the International System of Units. It is equal to the energy transferred to (or work done on) an object when a force of one newton acts on that object in the direction of the force's motion through a distance of one metre (1 newton-metre or N⋅m).

An imperial unit of power equal to 550 foot-pounds per second (about 750 watts).

The International System unit of electrical, mechanical, and thermal energy, equal to the work done when a force of one newton acts through a distance of one meter, and also equal to the work done when a current of one ampere is passed through a resistance of one ohm for one second.

Abbr. hp A unit of power in the US Customary System, equal to 745.7 watts or 33,000 foot-pounds per minute.

In the International System of Units, the derived unit of energy, work and heat; the work required to exert a force of one newton for a distance of one metre. Equivalent to one watt of power for a duration of one second. Symbol: J

The power exerted by a horse in pulling.

A unit of work which is equal to 107 ergs (the unit of work in the C. G. S. system of units), and is equivalent to one watt-second, the energy expended in one second by an electric current of one ampere in a resistance of one ohm; also called the absolute joule. It is abbreviated J or j. The international joule is slightly larger, being 1.000167 times the absolute joule. The absolute joule is approximately equal to 0.737562 foot pounds, 0.239006 gram-calories (small calories), and 3.72506 x 10-7 horsepower-hours, and 0.000948451 B.t.u.

(Informal) Effective strength

A unit of electrical energy equal to the work done when a current of one ampere passes through a resistance of one ohm for one second

(uncountable) Power derived from the motion of a horse.

English physicist who established the mechanical theory of heat and discovered the first law of thermodynamics (1818-1889)

A nonmetric unit of power (symbol hp) with various definitions, for different applications. The most common of them is probably the mechanical horsepower, approximately equal to 745.7 watts.

A metric unit (symbol often PS from the German abbreviation), approximately equal to 735.5 watts.

(uncountable) Strength.

A unit of power equal to 746 watts