Convert Grains to Carats
1 grain (gr) equals 0.32399455 carats (ct).
1 gr = 0.32399455 ct
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk grain to carat converter to paste a column from Excel.
How to Convert Grain to Carat
- 1 gr = 0.32399455 ct
- 1 ct = 3.086471671 gr
- Example: convert 15 gr to ct: 15 gr = 15 × 0.32399455 ct = 4.85991825 ct
Reference conditions. gr: Avoirdupois system: 1 lb = 16 oz = 7000 grains = 0.45359237 kg exactly (1959 agreement).
Formula
ct = gr × 0.32399455
or ct = gr ÷ 3.086471670588
Derivation from SI units:
- 1 gr = 1/7000 lb = 64.79891 mg (exact)
- 1 ct = 200 mg (metric carat, exact)
- 1 gr = 0.00006479891 kg ÷ 0.0002 kg per ct = 0.32399455 ct
Both units are defined exactly, so the factor is exact. Grain definition: grain; Carat definition: carat.
Worked examples
- A reading of 40 gr converts to 12.959782 ct.
40 gr × 0.32399455 = 12.959782 ct - A value of 150 gr is 48.5991825 ct.
150 gr × 0.32399455 = 48.5991825 ct
Grain to Carat conversion table
| Grains (gr) | Carats (ct) |
|---|---|
| 1 gr | 0.32399455 ct |
| 5 gr | 1.61997275 ct |
| 10 gr | 3.2399455 ct |
| 15 gr | 4.85991825 ct |
| 20 gr | 6.479891 ct |
| 40 gr | 12.959782 ct |
| 55 gr | 17.81970025 ct |
| 100 gr | 32.399455 ct |
| 115 gr | 37.25937325 ct |
| 124 gr | 40.1753242 ct |
| 150 gr | 48.5991825 ct |
| 180 gr | 58.319019 ct |
| 300 gr | 97.198365 ct |
| 1000 gr | 323.99455 ct |
| 7000 gr | 2267.96185 ct |
Where it's used
Grains are used for bullet and powder weights, while carats appear in diamonds and gemstones. Both measure mass (commonly called weight), so the conversion is a fixed factor.
Grain to other weight and mass units
| Conversion | 1 gr equals |
|---|---|
| grain to kilogram | 0.00006479891 kg |
| grain to gram | 0.06479891 g |
| grain to milligram | 64.79891 mg |
| grain to microgram | 64798.91 µg |
| grain to metric ton | 6.479891 × 10⁻⁸ t |
| grain to pound | 0.0001428571429 lb |
| grain to ounce | 0.002285714286 oz |
| grain to stone | 0.00001020408163 st |
| grain to short ton | 7.142857143 × 10⁻⁸ ton (US) |
| grain to long ton | 6.37755102 × 10⁻⁸ ton (UK) |
| grain to troy ounce | 0.002083333333 oz t |
| grain to carat | 0.32399455 ct |
Frequently asked questions
How many carats are in 1 grain?
1 gr = 0.32399455 ct.
How do I convert grains to carats?
Multiply the value in gr by 0.32399455, or divide it by 3.086471671. For example, 15 gr × 0.32399455 = 4.85991825 ct.
Is the gr to ct conversion exact?
Yes. Both units are defined exactly, and 1 gr is exactly 0.32399455 ct.
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, "grain (gr)".
- 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".
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 Grains to Carats. Retrieved October 17, 2026, from https://scientificconverters.com/mass/grains-to-carats/
IEEE
Scientific Converters, "Convert Grains to Carats," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/mass/grains-to-carats/