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Convert Foot-pound to Joule

Please provide values below to convert foot-pound [ft*lbf] to joule [J], or vice versa.



Definition: A foot-pound (ft·lb or ft·lbf) is a unit of work or energy in the imperial and United States customary systems of units. It is defined as the energy transferred when a force of one pound-force is applied over a linear displacement of one foot.

History/origin: The foot-pound is an English Engineering unit that is part of the British Gravitational system, based on the foot-pound-second (FPS) system. The FPS system is built using the units of foot for length, avoirdupois pound for mass or force, and the second for time.

Current use: The foot-pound is used in countries that have not adopted the International System of Units (SI). The United States is one of the largest countries where the foot-pound is still used in certain applications, though even in the US, the joule is preferred in most scientific contexts.


Definition: A joule (symbol: J) is a derived unit of energy in the International System of Units (SI). It is defined as the energy transferred to an object when a one newton force is applied to the object in the direction of its motion through a distance of one meter. It is also defined as the energy dissipated as heat when a 1 ampere electric current passes through a resistance of one ohm in the course of one second. It has a number of representations both in SI base units as well as other SI units such that:

J = kg·m2/s2 = N·m = Pa·m3 = W·s = C·V

History/origin: The unit, joule, is named after James Prescott Joule, an English physicist and mathematician who helped develop the Kelvin scale. He also discovered the relationship between heat and mechanical work, leading to the law of conservation of energy, and subsequently, the first law of thermodynamics.

Current use: As an SI derived unit, the joule is used within a variety of scientific contexts. Practical examples of energy measurement using joules include the energy required to lift objects, the energy released when objects fall, the heat required to raise temperature, and the kinetic energy of moving objects.

One of the dimensional representations of a joule is the N·m (Newton-meter), which is equivalent to the SI unit for torque. These units however, are different, and should be considered as such. Even though the joule is algebraically equal to the N·m, the N·m should not be used to represent the joule whenever possible, to avoid confusion with torque.

Foot-pound to Joule Conversion Table

Foot-pound [ft*lbf]Joule [J]
0.01 ft*lbf0.0135581795 J
0.1 ft*lbf0.1355817948 J
1 ft*lbf1.3558179483 J
2 ft*lbf2.7116358966 J
3 ft*lbf4.0674538449 J
5 ft*lbf6.7790897414 J
10 ft*lbf13.5581794829 J
20 ft*lbf27.1163589658 J
50 ft*lbf67.7908974145 J
100 ft*lbf135.581794829 J
1000 ft*lbf1355.8179482896 J

How to Convert Foot-pound to Joule

1 ft*lbf = 1.3558179483 J
1 J = 0.7375621493 ft*lbf

Example: convert 15 ft*lbf to J:
15 ft*lbf = 15 × 1.3558179483 J = 20.3372692243 J

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