Convert Grain (gr) to Pound-force Square Second/Foot (lbf·s²/ft) instantly.
About these units
Grain (gr)
The grain, defined as exactly 64.79891 milligrams, is one of the oldest units of mass still in limited use today. Derived from the weight of average cereal grains such as barley or wheat, it became a universal tiny unit used across Europe for coins, medicine, and gunpowder. The grain persists in firearms and ammunition manufacturing because bullet weights are still listed in grains (e.g., a "150-grain bullet"). Reloaders and ballistic engineers rely on the grain as a fine unit suitable for measuring powder charges and projectile masses. It is also used in traditional gold and silver transactions, linking it to the troy system. The grain's longevity highlights how ancient agrarian measures can remain embedded in modern technological practices.
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.