Grain
Also: gr, Troy grain
The grain (abbreviation: gr) is the smallest unit of the troy weight system and equals exactly 0.06479891 grams.
The grain (abbreviation: gr) is the smallest unit of the troy weight system and thus one of the oldest units of measurement still in use in precious metals trading. Historically the grain derived from the average weight of a grain of wheat - a reference common in many medieval trading cultures. Since international standardisation the value has been exact: 1 grain = 0.06479891 grams.
Position within the troy system
The troy weight system - the basis of all precious metal weights worldwide - is structured hierarchically:
| Unit | Grain | Grams |
|---|---|---|
| 1 grain | 1 gr | 0.064799 g |
| 1 pennyweight | 24 gr | 1.555174 g |
| 1 troy ounce (troy ounce) | 480 gr | 31.103477 g |
| 1 troy pound | 5 760 gr | 373.241722 g |
The grain is identical in the troy and avoirdupois systems - the only value the two systems share. Nevertheless the avoirdupois ounce (437.5 gr) differs markedly from the troy ounce (480 gr), which can lead to confusion in everyday trading.
Conversion
1 troy ounce = 480 grain = 31.1035 g
1 grain = 1/480 troy ounce ~ 0.002083 troy oz
Use the unit converter to convert grains quickly into grams, pennyweight or troy ounces.
Practical significance today
In modern precious metals trading the grain plays a role above all in the following areas:
- Coin specifications: American coinage laws (e.g. the Coinage Act) define the weights of historical coins in grains.
- Firearms: powder and projectile weights are still stated in grains in the USA today.
- Pharmacy (historical): apothecary weights used the grain as a base unit; today replaced by the metric system.
- Jewellery and dental alloys: occasionally encountered in describing historical dental gold alloys.
For the melt value calculator or the gold calculator, grams and troy ounces are the relevant input quantities; the grain serves there as an intermediate unit in conversion.
Distinction: grain vs. carat vs. gram
The grain must not be confused with the carat as a diamond weight (1 ct = 0.2 g) or the carat as a measure of gold fineness (e.g. 18 carat = 750 ‰) - entirely different concepts that merely sound similar.
In brief
The grain is a precisely defined, unchanging unit (0.06479891 g) with a long history. Anyone breaking troy ounces down into the smallest sub-units or looking up historical coin weights cannot avoid the grain.