grain [gr] Unit Converter

Definition of grain [gr] unit

A grain (symbol: gr) is a traditional unit of mass equal to exactly 64.79891 milligrams, or 1/7,000 of an avoirdupois pound. It is used chiefly for measuring very small masses, especially bullets, ammunition, precious metals, and some medicines.

History of grain [gr] unit

The grain is one of the oldest units of mass. In ancient times, it was associated with the mass of a barleycorn or wheat grain, although historical standards varied. English weighing systems later incorporated it into the troy and avoirdupois systems. Under the troy system, 5760 grains equal a pound; under avoirdupois, 7000 grains equal a pound. In 1959, the international yard and pound agreement defined the grain as exactly 64.79891 milligrams, providing a fixed modern value for scientific, commercial, and technical use.

Applications of grain [gr] unit

Today, grains remain common in ballistics, where bullet and propellant weights are specified in grains. They also appear in descriptions of arrow points, gunpowder charges, and some precious metal weights. In pharmacology, the grain was formerly used for drug dosages, though metric units now dominate. Reloaders, ammunition manufacturers, and firearms references continue using the unit because of established standards and compatibility.

Complete list of grain [gr] unit conversion