Convert Pound (lb) to Pound-force Square Second/Foot (lbf·s²/ft) instantly.
About these units
Pound (lb)
The pound is a traditional unit of mass widely used in the United States and, to a lesser extent, in the United Kingdom. Defined as exactly 0.45359237 kilograms, the pound evolved from medieval English systems that themselves descended from Roman and Carolingian traditions. The pound is central to commerce, engineering, food measurement, and body weight scales in the US. Its widespread cultural presence makes it deeply familiar even in contexts where metric units dominate. Because the pound is part of a non-decimal system, subdivisions such as ounces (1/16 pound) introduce complexity, yet this structure persists due to tradition and embedded industrial standards. In engineering, the pound often appears alongside pound-force, making careful distinction between mass and force essential.
Pound-force Square Second/Foot (lbf·s²/ft)
This unit is part of the British Gravitational System, where mass is defined from force rather than the other way around. It can be interpreted as an inertial mass unit, since applying 1 pound-force to it would produce an acceleration of 1 foot per second squared. Historically, before the SI system clarified the distinction between force and mass, engineering fields often used mixed systems where pounds could represent either force (lbf) or mass (lbm). The unit lbf·s²/ft was introduced to straighten out these ambiguities in dynamic calculations such as impact forces, mechanical oscillations, and safety load computations. Today, the unit survives mostly in engineering textbooks, legacy calculations, and historical documentation. It demonstrates how complex and inconsistent measurement systems once were, and why global scientific communities moved toward SI clarity.