Convert Grains to Carats
1 grain is 0.32 ct. One grain is exactly 0.32399455 carats.
One grain is 0.32399455 carats. To convert grains to carats, multiply by 0.32399455; to go the other way, divide by 0.32399455 or multiply by 3.0864717. The factor is exact rather than rounded: it follows from NIST Handbook 44. Exactly 64.79891 milligrams, the unit both the avoirdupois and troy systems are built from.
Factor checked against the defining standard · How we check
- Grains × 0.32399455
1 * 0.32399450.324 ct
1 grain in every weight unit
| Unit | Value | Exact factor |
|---|---|---|
| ounces | 0.002285714286 oz | × 0.00228571428571 |
| pounds | 0.0001428571429 lb | × 0.000142857142857 |
| stone | 0.00001020408163 st | × 0.0000102040816327 |
| US tons | 0.00000007142857143 ton | × 0.0000000714285714286 |
| micrograms | 64,798.91 mcg | × 64,798.91 |
| milligrams | 64.79891 mg | × 64.79891 |
| centigrams | 6.479891 cg | × 6.479891 |
| grams | 0.06479891 g | × 0.06479891 |
| kilograms | 0.00006479891 kg | × 0.00006479891 |
| slugs | 0.000004440135739 slug | × 0.0000044401357388 |
| tonnes | 0.00000006479891 t | × 0.00000006479891 |
| carats | 0.32399455 ct | × 0.32399455 |
| troy ounces | 0.002083333333 ozt | × 0.00208333333333 |
| grains (as entered) | 1 gr | — |
| long tons | 0.0000000637755102 LT | × 0.0000000637755102041 |
Factors are entered by hand from NIST Handbook 44 rather than derived from a units library, so the ones that terminate are exact rather than rounded.
How do you convert grains to carats? The converter and the working
- 1.Take the measurement in grains.
- 2.Multiply by 0.32399455 — that is how many carats fit in one grain.
- 3.To go back the other way, divide by 0.32399455, or multiply by 3.0864717.
Worked example: 25 grains to carats
- Formula
- gr × 0.32399455 = ct
- Arithmetic
- 25 × 0.32399455 = 8.1 ct
- Answer
- 25 gr = 8.1 ct
The factor is exact, so this figure is exact too — only the display is rounded.
Grains to carats conversion table
| Grains | Carats |
|---|---|
| 1 gr | 0.32 ct |
| 2 gr | 0.65 ct |
| 3 gr | 0.97 ct |
| 4 gr | 1.3 ct |
| 5 gr | 1.62 ct |
| 6 gr | 1.94 ct |
| 7 gr | 2.27 ct |
| 8 gr | 2.59 ct |
| 9 gr | 2.92 ct |
| 10 gr | 3.24 ct |
| 12 gr | 3.89 ct |
| 15 gr | 4.86 ct |
| 20 gr | 6.48 ct |
| 25 gr | 8.1 ct |
| 50 gr | 16.2 ct |
| 100 gr | 32.4 ct |
| 200 gr | 64.8 ct |
| 300 gr | 97.2 ct |
| 500 gr | 162 ct |
| 1000 gr | 323.99 ct |
| 2000 gr | 647.99 ct |
| 5000 gr | 1,619.97 ct |
| 10000 gr | 3,239.95 ct |
What is a grain?
Exactly 64.79891 milligrams, the unit both the avoirdupois and troy systems are built from. Bullet weights and powder charges are still measured in it, and so are some pharmaceutical doses.
What is a carat?
Exactly 200 milligrams, fixed by international agreement in 1907 after centuries of local carats. It weighs a gemstone; the karat that grades gold is a different word for a different thing — purity in twenty-fourths.
How many carats are in a grain?
One grain is 0.32399455 carats, exactly. Going the other way, one carat is 3.0864717 grains. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.
Every weight unit here
The whole group — 15 units with their symbols and the size of each one in kilograms — is on the conversion index, along with every pair it makes. The table above already gives each of them relative to a grain.
Cite this page
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- Rule Calculator. (2026). Convert Grains to carats. Rule Calculator. https://rulecalculators.com/convert/grain-to-carat
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- Chicago
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Questions people actually ask
- How many carats are in a grain?
- 0.32399455. Exactly 200 milligrams, fixed by international agreement in 1907 after centuries of local carats. It weighs a gemstone; the karat that grades gold is a different word for a different thing — purity in twenty-fourths.
- How do I convert carats back to grains?
- Divide by 0.32399455, or multiply by 3.0864717 — they are the same operation.
Other weight conversions
Carats to grains — the same conversion the other way.