Convert Pound-force Square Second/Foot (lbf·s²/ft) to Kilopound (kip) instantly.
About these units
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.
Kilopound (kip)
A kilopound, or kip, equals 1,000 pounds and is used primarily in structural engineering, especially in the United States. Loads, tensions, and compression forces in steel beams, concrete structures, and bridges are often expressed in kips. The kip allows engineers to avoid large numbers when expressing forces such as building loads or material stresses. In structural analysis software and construction documents, kips are ubiquitous. Despite not being a mass unit strictly speaking (it is often used as a force unit, kip-force), it remains central to American engineering practice.