A grain is exactly 64.79891 milligrams.
Grains to Carats Converter — gr to ct
Convert Grain (gr) to Carat (ct) using the exact conversion factor (1 grain = 0.32399455 carat). See the formula, worked examples, and conversion table.
Grains to Carats converter
Converter
Mass/Weight Converter
Convert SI mass, imperial weight, jewelry, atomic, and astronomy mass units.
Context values
Some unit families need one extra value for a physically accurate result.
A metric carat is exactly 200 milligrams.
Result = input x 6.479891e-5 / 0.0002.
Mass uses the kilogram as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Grains to Carats
Weight conversions between Grain and Carat come up constantly in everyday commerce, shipping, and cooking, since US packaging is usually labeled in pounds while most of the rest of the world uses kilograms. Specifically: A grain is exactly 64.79891 milligrams, and a metric carat is exactly 200 milligrams.
Formula
carats = grains × 0.32399455
This factor comes from each unit's defined relationship to the category's base unit: 1 grain equals 0.00006479891 base units, and 1 carat equals 0.0002 base units, so dividing one by the other gives the direct grain-to-carat factor of 0.32399455.
Simple example
1 gr × 0.32399455 = 0.32399455 ct
1 grain = 0.32399455 carats.
Real-world example
50 gr × 0.32399455 = 16.1997275 ct
50 grains = 16.1997275 carats.
Conversion table
| Grain (gr) | Carat (ct) |
|---|---|
| 1 gr | 0.32399455 ct |
| 5 gr | 1.61997275 ct |
| 10 gr | 3.2399455 ct |
| 25 gr | 8.09986375 ct |
| 50 gr | 16.1997275 ct |
| 100 gr | 32.399455 ct |
Reverse conversion: Carat to Grain
0.32399455 ct × 3.086471671 = 1 gr
0.32399455 carats = 1 grains.
grains = carats × 3.08647167059
For a page dedicated to this direction, see Carat to Grain.
Understanding the Grain (gr)
A grain is exactly 64.79891 milligrams.
Understanding the Carat (ct)
A metric carat is exactly 200 milligrams.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many carats are in 1 grain?
1 grain equals 0.32399455 carats, using the exact defined conversion factor rather than an estimate.
How do I convert grain to carat?
Multiply the grain value by 0.32399455. The converter above does this instantly to whatever precision you set.
How do I convert carat back to grain?
Use the reverse factor: 1 carat equals 3.086471671 grains. You can also use the swap control in the converter above to flip the direction instantly.
What is a grain?
Grain (gr) is a unit of mass/weight.
What is a carat?
Carat (ct) is a unit of mass/weight.
Is the grain to carat conversion exact?
Yes. Both grain and carat are defined by fixed standards rather than physical artifacts, so the factor of 0.32399455 used above is exact to as many digits as you choose to display.