| pound-foot | |
|---|---|
 Pound-foot andkilogram-force-metre are displayed on thistorque wrench. | |
| General information | |
| Unit system | British Gravitational System,English Engineering Units |
| Unit of | Torque |
| Symbol | lbf⋅ft, lb-ft |
| Conversions | |
| 1 lbf⋅ftin ... | ... is equal to ... |
| SI units | ≈ 1.355818 N⋅m[1] |
| Gravitational metric system | ≈ 0.1382550 kgf⋅m |
Apound-foot (lb⋅ft), abbreviated frompound-force foot (lbf · ft), is a unit oftorque representing onepound of force acting at a perpendicular distance of onefoot from a pivot point.[2] Conversely one foot pound-force (ft · lbf) is themoment about an axis that applies one pound-force at a radius of one foot.
The value inSystème International (SI) units is given by multiplying the following exact factors:
This gives the exact conversion factor:
The name "pound-foot", intended to minimize confusion with thefoot-pound as a unit ofwork, was apparently first proposed by British physicistArthur Mason Worthington.[3]
Despite this, in practice torque units are commonly called the foot-pound (denoted as either lb-ft or ft-lb) or the inch-pound (denoted as in-lb).[4][5] Practitioners depend on context and the hyphenated abbreviations to know that these refer to neither energy nor moment of mass (as the symbol ft-lb rather than lbf-ft would imply).
Similarly, aninch-pound (orpound-inch) is the torque of one pound of force applied to one inch of distance from the pivot, and is equal to1⁄12 lbf⋅ft (0.1129848 N⋅m). It is commonly used ontorque wrenches andtorque screwdrivers for setting specific fastener tension. Aninch-ounce is a smaller unit, equal to1⁄16 of an inch-pound.