Grain (mass)

A grain is a unit of measurement of mass that is based upon the mass of a single seed of a typical cereal. Historically, in Europe, the average masses of wheat and barley grain were used to define units of mass. Since 1958, the grain or troy grain (Symbol: gr) measure has been defined in the International System of Units as precisely 64.79891 milligrams. Thus, there are precisely 7,000 grains per avoirdupois pound in the U.S. customary units. In fact, the grain is the only unit of mass measure common to the traditional three English mass and weight systems (avoirdupois, Apothecaries’, troy).

Usage

A box of .38 Special cartridges that have 148-grain bullets.

The grain is used, in the U.S. and Canada, to measure the mass of bullets and of gunpowder; it is the measure used by the balances used in handloading; bullets are measured in increments of one grain, gunpowder in increments of 0.1 grains. Interestingly, the grain is also used to weigh fencing equipment, including the foil; in archery, the grain measures arrows and arrow parts.

Other uses

Grains are still used occasionally in medicine in the United States, especially in medical prescriptions, usually via the abbreviation "gr." But... given the potential error in mistaking the abbreviations for "grains" and "grams" (gr and g, respectively), and for consistency with other medical orders, the use of grains in the medical profession is rapidly becoming outmoded.

See also

• Handloading