Convert Carats to Grams
1 carat (ct) equals 0.2 grams (g).
Converting a list? Use the bulk carat to gram converter to paste a column from Excel.
How to Convert Carat to Gram
- 1 ct = 0.2 g
- 1 g = 5 ct
- Example: convert 15 ct to g: 15 ct = 15 × 0.2 g = 3 g
Formula
g = ct ÷ 5
Derivation from SI units:
- 1 ct = 200 mg (metric carat, exact)
- 1 g = 10⁻³ kg
- 1 ct = 0.0002 kg ÷ 0.001 kg per g = 0.2 g
Both units are defined exactly, so the factor is exact. Carat definition: carat; Gram definition: gram.
Worked examples
- A 1 ct diamond weighs 0.2 g.
1 ct × 0.2 = 0.2 g - A 5 ct sapphire weighs 1 g.
5 ct × 0.2 = 1 g
Carat to Gram conversion table
| Carats (ct) | Grams (g) |
|---|---|
| 0.1 ct | 0.02 g |
| 0.25 ct | 0.05 g |
| 0.5 ct | 0.1 g |
| 0.75 ct | 0.15 g |
| 1 ct | 0.2 g |
| 1.5 ct | 0.3 g |
| 2 ct | 0.4 g |
| 3 ct | 0.6 g |
| 5 ct | 1 g |
| 10 ct | 2 g |
| 100 ct | 20 g |
Where it's used
Gemstone weights in carats are converted to grams for shipping, insurance and comparison with other materials. 1 ct = 0.2 g exactly.
Carat to other weight and mass units
| Conversion | 1 ct equals |
|---|---|
| carat to kilogram | 0.0002 kg |
| carat to gram | 0.2 g |
| carat to milligram | 200 mg |
| carat to microgram | 200000 µg |
| carat to metric ton | 2 × 10⁻⁷ t |
| carat to pound | 0.0004409245244 lb |
| carat to ounce | 0.00705479239 oz |
| carat to stone | 0.00003149460888 st |
| carat to short ton | 2.204622622 × 10⁻⁷ ton (US) |
| carat to long ton | 1.968413055 × 10⁻⁷ ton (UK) |
| carat to grain | 3.086471671 gr |
| carat to troy ounce | 0.006430149314 oz t |
Frequently asked questions
Is carat the same as karat?
No. The carat (ct) measures gemstone mass, 200 mg; the karat (K) expresses gold purity in 24ths.
How many grams are in 1 carat?
1 ct = 0.2 g.
How do I convert carats to grams?
Multiply the value in ct by 0.2, or divide it by 5. For example, 15 ct × 0.2 = 3 g.
Is the ct to g conversion exact?
Yes. Both units are defined exactly, and 1 ct is exactly 0.2 g.
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "carat, metric".
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 7, SI prefixes.
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Carats to Grams. Retrieved October 17, 2026, from https://scientificconverters.com/mass/carats-to-grams/
IEEE
Scientific Converters, "Convert Carats to Grams," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/mass/carats-to-grams/