Foot-pound

In physics, a foot-pound (symbol ft·lbf or ft·lb_f) is an Imperial and U.S. customary unit of mechanical work, or energy, although in scientific fields one commonly uses the equivalent metric unit of the joule (J). There are approximately 1.356 J/(ft·lb_f).

To calculate a foot-pound, you can use this formula,

W = F × D

where W is work (in foot-pounds), F is force (in pounds), and D is distance (in feet) over which the force is applied (measured in the direction of the force).

The foot-pound is also the unit of torque, which is conventionally expressed in SI units as newton-meters rather than joules. Sometimes the order of the units is reversed for torque, expressed as pound-feet rather than foot pounds.

Doing 550 foot-pounds of work on an object in one second is equal to a horsepower, an Imperial and U.S. customary unit of power.