Carats to Grains (ct to gr) Converter
1 Carat equals 3.0865 Grains (1 ct = 3.0865 gr). Convert Carats to Grains with formula, table, and examples.
One carat equals approximately 3.0865 grains. The grain is one of the oldest and most persistent weight units, identical across the troy, avoirdupois, and apothecary systems at exactly 64.79891 milligrams. Since a carat is 200 milligrams, each carat contains just over three grains, making this a practical conversion for jewelers and pharmacists working across historical measurement systems.
How to Convert Carats to Grains
- Take your value in Carats
- Multiply by 3.0864716706
- Read the result in Grains
Common Carats to Grains Conversions
| Carats (ct) | Grains (gr) | Status |
|---|---|---|
| 0.25 ct | 0.7716 gr | |
| 0.5 ct | 1.5432 gr | |
| 1 ct | 3.0865 gr | |
| 2 ct | 6.1729 gr | |
| 3 ct | 9.2594 gr | |
| 5 ct | 15.4324 gr | |
| 10 ct | 30.8647 gr | |
| 25 ct | 77.1618 gr | |
| 50 ct | 154.3236 gr | |
| 100 ct | 308.6472 gr | |
| 250 ct | 771.6179 gr | |
| 500 ct | 1,543.2358 gr | |
| 1,000 ct | 3,086.4717 gr | |
| 5,000 ct | 15,432.3584 gr |
Good to Know About Carats to Grains Conversion
The grain is remarkable for being the one unit that survived unchanged across all three English weight systems. When Parliament standardized weights and measures, the grain served as the common anchor: 7,000 grains made one avoirdupois pound, 5,760 grains made one troy pound. This shared foundation is why the grain could serve as a Rosetta Stone for converting between the otherwise incompatible systems.
Carats to Grains: What You Need to Know
Grains remain actively used in ammunition (bullet weights are specified in grains), archery (arrow spine and point weight), and some pharmaceutical dosages. A typical aspirin tablet weighs about 5 grains (325 mg), which is roughly 1.625 carats. Diamond traders rarely think in grains, but antique jewelry documentation sometimes recorded gemstone weights this way, requiring conversion for modern appraisals.
What is a Carat? ct
A carat is a unit of mass equal to exactly 200 milligrams (0.2 grams), used for measuring gemstones and pearls. Adopted internationally in 1907 by the Fourth General Conference on Weights and Measures.
Learn more about Carat →What is a Grain? gr
A grain is a unit of mass equal to exactly 64.79891 milligrams. It is the same in the avoirdupois, troy, and apothecaries' systems, derived from the 1959 international agreement defining the pound as exactly 0.45359237 kilograms.
Learn more about Grain →Going the other way? Use our Grains to Carats converter.
Carats to Grains FAQ
-
One carat equals approximately 3.0865 grains. This is derived from 1 carat being exactly 200 milligrams and 1 grain being approximately 64.799 milligrams.
-
Yes. The grain is uniquely consistent: 1 grain equals exactly 64.79891 milligrams in the troy, avoirdupois, and apothecary systems. It is the only unit shared identically across all three traditional English weight systems.
-
Grains are actively used in ammunition manufacturing (bullet and powder charge weights), archery (arrow component weights), and some pharmaceutical compounding. They also appear in water hardness measurements (grains per gallon).
Non-Frequently Asked Questions About Carats to Grains
Questions nobody should ask - but someone did.
-
Yes. The grain was originally defined as the weight of a single grain of barley or wheat, taken from the middle of the ear. Of course, individual grains vary considerably in weight, which is why medieval measurement was more of an art than a science. The modern grain is standardized and no longer depends on the agricultural output of any particular field.
-
The grain unit and a grain of rice are very different things. A single grain of uncooked rice weighs about 25 to 30 milligrams, meaning one carat (200 mg) weighs as much as roughly 7 to 8 grains of rice. The rice is significantly cheaper per grain.
Related Articles About Carats to Grains
Need the reverse? Use our Grains to Carats converter. See all Weight & Mass converters.