Pound-force

The pound-force (symbol: lbf&thinsp; &thinsp;) is a measurement unit of force which will accelerate 1 pound of mass to 9.80665 m/s2 (≈&thinsp;32.17405 ft/s2), the standard average acceleration due to gravity on Earth's surface (referred to as gn&thinsp; ). It is used primarily in the United States and is equivalent to exactly 4.4482216152605 newtons.

In common usage and other contexts, it is most often referred to in the United States as a pound or as lb, but this can lead to confusion with the pound-mass.

Definition in terms of the SI unit of force
The newton (symbol: N) is the unit of force named in the International System of Units (SI). Using the standard average acceleration due to gravity, denoted gn, as being 9.80665 m/s2 and the internationally agreed upon definition of the pound-mass, denoted as lbm, as being 0.45359237 kg, we can determine the number of newtons exactly equivalent to a pound-force:


 * $$\begin{align}1\,\mathrm{lbf} &\equiv 1\,\mathrm{lbm} \cdot g_n \\

&\equiv 0.45359237\,\mathrm{kg} \cdot 9.80665\,\mathrm{{m}/{s^2}}\\ &\equiv 4.4482216152605\,\mathrm{N} \end{align}$$

Equivalent units of force

 * 1 lbf &asymp; 4.448221 newton (symbol: N)
 * 1 lbf &asymp; 4448822 dyne (symbol: dyn)
 * 1 lbf &asymp; 0.453592 kilogram-force (symbol: kgf)
 * 1 lbf &asymp; 0.453592 kilopond (symbol: kp)
 * 1 lbf &asymp; 4.448221×10−3 sthène (symbol: sn)
 * 1 lbf &asymp; 32.17405 poundal (symbol: pdl)
 * 1 lbf &equiv; 0.001 kip (symbol: kip)