Grain (unit)

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File:148 grain 38 special.jpg

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Unit of mass

Unit system	Imperial / US customary
Unit of	Mass
Symbol	gr
Named after

The grain is a unit of mass that is based on the mass of a single seed of a cereal grain, such as wheat or barley. It is the smallest unit of mass in the imperial and US customary systems, and it is equal to exactly 64.79891 milligrams.

History

The grain was historically used as a standard unit of mass in the troy weight, avoirdupois, and apothecaries' systems. It originated from the weight of a single grain of barley, which was considered a reliable and consistent measure. The grain has been used since ancient times and was standardized in the 13th century by Henry III of England.

Usage

The grain is commonly used in the measurement of bullet and propellant weights in ballistics, as well as in the measurement of jewelry and precious metals. It is also used in medicine to measure the dosage of certain medications, particularly in pharmaceutical compounding.

Conversion

One grain is equal to:

• 0.06479891 grams
• 64.79891 milligrams
• 1/7000 of a pound (avoirdupois)
• 1/5760 of a troy pound

Related Units

• Troy weight
• Avoirdupois
• Apothecaries' system
• Milligram
• Gram
• Ounce
• Pound

See Also

• Imperial units
• United States customary units
• Mass
• Weight
• Measurement

References

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