Convert Carats to Milligrams
1 carat (ct) equals 200 milligrams (mg).
1 ct = 200 mg
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk carat to milligram converter to paste a column from Excel.
How to Convert Carat to Milligram
- 1 ct = 200 mg
- 1 mg = 0.005 ct
- Example: convert 15 ct to mg: 15 ct = 15 × 200 mg = 3000 mg
Formula
mg = ct × 200
Derivation from SI units:
- 1 ct = 200 mg (metric carat, exact)
- 1 mg = 10⁻⁶ kg = 10⁻³ g
- 1 ct = 0.0002 kg ÷ 0.000001 kg per mg = 200 mg
Both units are defined exactly, so the factor is exact. Carat definition: carat; Milligram definition: milligram.
Worked examples
- A reading of 0.75 ct converts to 150 mg.
0.75 ct × 200 = 150 mg - A value of 3 ct is 600 mg.
3 ct × 200 = 600 mg
Carat to Milligram conversion table
| Carats (ct) | Milligrams (mg) |
|---|---|
| 0.1 ct | 20 mg |
| 0.25 ct | 50 mg |
| 0.5 ct | 100 mg |
| 0.75 ct | 150 mg |
| 1 ct | 200 mg |
| 1.5 ct | 300 mg |
| 2 ct | 400 mg |
| 3 ct | 600 mg |
| 5 ct | 1000 mg |
| 10 ct | 2000 mg |
| 100 ct | 20000 mg |
Where it's used
Carats are used for diamonds and gemstones, while milligrams appear in medication doses (e.g. 500 mg tablets). Both measure mass (commonly called weight), so the conversion is a fixed factor.
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
How many milligrams are in 1 carat?
1 ct = 200 mg.
How do I convert carats to milligrams?
Multiply the value in ct by 200. For example, 15 ct × 200 = 3000 mg.
Is the ct to mg conversion exact?
Yes. Both units are defined exactly, and 1 ct is exactly 200 mg.
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 Milligrams. Retrieved October 17, 2026, from https://scientificconverters.com/mass/carats-to-milligrams/
IEEE
Scientific Converters, "Convert Carats to Milligrams," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/mass/carats-to-milligrams/