A metric carat is exactly 200 milligrams.
Carats to Grams Converter — ct to g
Convert Carat (ct) to Gram (g) using the exact conversion factor (1 carat = 0.2 gram). See the formula, worked examples, conversion table, history, and common uses.
Carats to Grams 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 gram is one thousandth of a kilogram.
Result = input x 0.0002 / 0.001.
Mass uses the kilogram as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Carats to Grams
Weight conversions between Carat and Gram 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 metric carat is exactly 200 milligrams, and a gram is one thousandth of a kilogram.
Formula
grams = carats × 0.2
This factor comes from each unit's defined relationship to the category's base unit: 1 carat equals 0.0002 base units, and 1 gram equals 0.001 base units, so dividing one by the other gives the direct carat-to-gram factor of 0.2.
Simple example
1 ct × 0.2 = 0.2 g
1 carat = 0.2 grams.
Real-world example
50 ct × 0.2 = 10 g
50 carats = 10 grams.
Conversion table
| Carat (ct) | Gram (g) |
|---|---|
| 1 ct | 0.2 g |
| 5 ct | 1 g |
| 10 ct | 2 g |
| 25 ct | 5 g |
| 50 ct | 10 g |
| 100 ct | 20 g |
Reverse conversion: Gram to Carat
0.2 g × 5 = 1 ct
0.2 grams = 1 carat.
carats = grams × 5
For a page dedicated to this direction, see Gram to Carat.
Understanding the Carat (ct)
A metric carat is exactly 200 milligrams.
Understanding the Gram
Gram (g) measures mass. A gram is one-thousandth of a kilogram, the SI base unit of mass. It is classified as a SI derived (metric prefix) unit.
Where it's used: Standard small-mass unit worldwide
Uses of the Gram today
- Cooking and nutrition labeling worldwide (including in the US, alongside ounces)
- Precious metal and small-item weighing
- Scientific and laboratory measurement
History of the Gram
Originally defined in 1795 as the mass of one cubic centimeter of water, the gram follows directly from the kilogram (1/1000 of it) under the modern SI system, inheriting the kilogram's various historical and current definitions.
Historical origin. Gram was not the invention of a single named person; it developed through the process described above.
Gram — sources
- BIPM — The kilogram (SI base unit) — Basis for the gram as 1/1000 of the kilogram.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many grams are in 1 carat?
1 carat equals 0.2 grams, using the exact defined conversion factor rather than an estimate.
How do I convert carat to gram?
Multiply the carat value by 0.2. The converter above does this instantly to whatever precision you set.
How do I convert gram back to carat?
Use the reverse factor: 1 gram equals 5 carats. You can also use the swap control in the converter above to flip the direction instantly.
What is a carat?
Carat (ct) is a unit of mass/weight.
What is a gram?
Gram (g) measures mass. A gram is one-thousandth of a kilogram, the SI base unit of mass. It is classified as a SI derived (metric prefix) unit.
Is the carat to gram conversion exact?
Yes. Both carat and gram are defined by fixed standards rather than physical artifacts, so the factor of 0.2 used above is exact to as many digits as you choose to display.