Grain
Also: gr, Troy Grain
The grain (abbreviated gr) is the smallest unit in the troy weight system and equals exactly 0.06479891 grams.
The grain (abbreviated gr) is the smallest unit in the troy weight system and one of the oldest measures still in everyday use in the precious-metals trade. Historically the grain derived from the average weight of a grain of wheat — a reference common across many medieval trading cultures. Since international standardisation its value has been fixed precisely: 1 grain = 0.06479891 grams.
Where it sits in the troy system
The troy weight system — the basis for every precious-metal weight worldwide — is arranged in a hierarchy:
| Unit | Grains | 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 single value the two systems share. Even so, the avoirdupois ounce (437.5 gr) differs markedly from the troy ounce (480 gr), which can cause confusion in day-to-day trading.
Conversion
1 troy ounce = 480 grains = 31.1035 g
1 grain = 1/480 troy ounce ≈ 0.002083 troy oz
Use the unit converter to turn grains quickly into grams, pennyweights or troy ounces.
Practical relevance today
In the modern precious-metals trade the grain still matters mainly in these areas:
- Coin specifications: American coinage law (such as the Coinage Act) defines the weights of historical coins in grains.
- Firearms: powder and projectile weights are still quoted in grains in the United States.
- Pharmacy (historical): apothecary weights used the grain as a base unit; it has since been replaced by the metric system.
- Jewellery and dental alloys: occasionally seen when describing historical dental gold alloys.
For the melt value calculator or the gold calculator, grams and troy ounces are the relevant inputs; the grain serves there only as an intermediate unit during conversion.
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 karat as a measure of gold fineness (for example 18 karat = 750 ‰) — entirely different concepts that merely sound alike.
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 will inevitably meet the grain.