Foot-pound

Physical unit
Unit name	foot-pound
Unit symbol	${\displaystyle \mathrm {ft\cdot lb} }$
Physical quantity (s)	energy
Formula symbol	${\displaystyle W\,E}$
dimension	${\displaystyle {\mathsf {M\;L^{2}\;T^{-2}}}}$
system	Anglo-American system of measurement
In SI units	${\displaystyle \mathrm {1\,ft\cdot lb\;\approx \;1{,}355\,817\,948\;J} }$
In CGS units	${\displaystyle \mathrm {1\,ft\cdot lb\;\approx \;13\,558\,179{,}48\;erg} }$
Derived from	Foot , pound

Physical unit
Unit name	Pound-foot
Unit symbol	${\displaystyle \mathrm {ft\cdot lb} }$
Physical quantity (s)	Torque
Formula symbol	${\displaystyle M}$
dimension	${\displaystyle {\mathsf {M\;L^{2}\;T^{-2}}}}$
system	Anglo-American system of measurement
In SI units	${\displaystyle \mathrm {1\,ft\cdot lb\;\approx \;1{,}355\,817\,948\;Nm} }$
In CGS units	${\displaystyle \mathrm {1\,ft\cdot lb\;\approx \;13\,558\,179{,}48\;dyn\cdot cm} }$
Derived from	Foot , pound

The foot-pound or foot-pound force is a British and American unit of both energy and torque (there also pound-foot ). The unit symbol is ft lb or ft lbf , also lbf ft .

One foot-pound is exactly 1.355 817 948 331 400 4  J ( Joule ) and corresponds to the energy that has to be applied to lift a body with a mass of one pound by one foot against its weight :

${\displaystyle {1\,\mathrm {ft} \cdot \mathrm {lb} =\mathrm {lb} \cdot g\cdot \mathrm {ft} =0{,}45359237\,\mathrm {kg} \cdot 9{,}81\,{\frac {\mathrm {m} }{\mathrm {s} ^{2}}}\cdot 0{,}3048\,\mathrm {m} =1{,}35581\dots \,\mathrm {kg} {\frac {\mathrm {m} ^{2}}{\mathrm {s} ^{2}}}=1{,}355\,817\,948\,331\,400\,4\,\mathrm {J} }}$

550 foot-pounds per second correspond to one hp (about 745.7 watts).