Grain
Also: gr, Troy grain
The grain (abbreviation: gr) is the smallest unit of the troy weight system and is exactly equal to 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 the precious metals trade. Historically, the grain derived from the average weight of a grain of wheat – a reference widespread 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 considerably 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 quickly convert grains into grams, pennyweights or troy ounces.
Practical importance today
In the modern precious metals trade, 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 field: Powder and projectile weights are still given in grains in the USA to this day.
- Pharmacy (historical): Apothecary weights used the grain as a base unit; today replaced by the metric system.
- Jewellery and dental alloys: Occasionally encountered in the description of historical dental gold alloys.
For the melt value calculator or the gold calculator, grams and troy ounces are the relevant input values; there the grain serves as an intermediate unit in the 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 gold fineness (e.g. 18 carat = 750 ‰) – completely different concepts that merely sound similar.
In brief
The grain is an exactly defined, unchanging unit (0.06479891 g) with a long history. Anyone breaking down troy ounces into the smallest sub-units or looking up historical coin weights cannot avoid the grain.