Convert Carats to Grains
Convert Carats (ct) to Grains (gr) instantly and accurately.
Conversion Formula
gr = ct × 3.086471671
About Carats
A metric carat (ct or CD) is exactly 200 milligrams (0.2 g), the universal standard for weighing gemstones. Established internationally in 1907, it replaced fractionally different regional carat weights previously used in different countries. The total weight of a diamond or colored gemstone is always expressed in carats: a 1.00 ct diamond of excellent cut and color can command over $5,000. The Cullinan diamond, the largest gem-quality rough diamond ever found, weighed 3,106.75 carats.
About Grains
A grain (gr) is the smallest unit in both the avoirdupois and troy weight systems, equal to exactly 64.79891 milligrams. Originally defined as the mass of a single grain of barley or wheat from the middle of an ear, it has been a standard of weight since ancient times. Today, grains are used to weigh gunpowder charges and bullets (a standard .308 rifle bullet weighs 168 gr), pharmaceutical preparations in apothecary compounding, and the fineness of gold alloys. Arrowhead and fishing hook weights are also specified in grains.
Quick Reference Table
| Carats (ct) | Grains (gr) |
|---|---|
| 1 ct | 3.08647 gr |
| 2 ct | 6.17294 gr |
| 5 ct | 15.4324 gr |
| 10 ct | 30.8647 gr |
| 25 ct | 77.1618 gr |
| 50 ct | 154.324 gr |
| 100 ct | 308.647 gr |