Convert Carats to Stone
1 carat (ct) equals 0.00003149460888 stone (st).
1 ct = 0.00003149460888 st
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk carat to stone converter to paste a column from Excel.
How to Convert Carat to Stone
- 1 ct = 0.00003149460888 st
- 1 st = 31751.4659 ct
- Example: convert 15 ct to st: 15 ct = 15 × 0.00003149460888 st = 0.0004724191333 st
Reference conditions. st: Avoirdupois system: 1 lb = 16 oz = 7000 grains = 0.45359237 kg exactly (1959 agreement).
Formula
st = ct × 0.00003149460888355
or st = ct ÷ 31751.4659
Derivation from SI units:
- 1 ct = 200 mg (metric carat, exact)
- 1 st = 14 lb = 6.35029318 kg (exact)
- 1 ct = 0.0002 kg ÷ 6.35029318 kg per st = 0.00003149460888355 st
Both units are defined exactly, so the factor is exact. Carat definition: carat; Stone definition: stone.
Worked examples
- A reading of 0.75 ct converts to 0.00002362095666 st.
0.75 ct × 0.00003149460888 = 0.00002362095666 st - A value of 3 ct is 0.00009448382665 st.
3 ct × 0.00003149460888 = 0.00009448382665 st
Carat to Stone conversion table
| Carats (ct) | Stone (st) |
|---|---|
| 0.1 ct | 0.000003149460888 st |
| 0.25 ct | 0.000007873652221 st |
| 0.5 ct | 0.00001574730444 st |
| 0.75 ct | 0.00002362095666 st |
| 1 ct | 0.00003149460888 st |
| 1.5 ct | 0.00004724191333 st |
| 2 ct | 0.00006298921777 st |
| 3 ct | 0.00009448382665 st |
| 5 ct | 0.0001574730444 st |
| 10 ct | 0.0003149460888 st |
| 100 ct | 0.003149460888 st |
Where it's used
Carats are used for diamonds and gemstones, while stone appear in body weight in the UK and Ireland (e.g. 11 st 6 lb). 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 stone are in 1 carat?
1 ct = 0.00003149460888 st.
How do I convert carats to stone?
Multiply the value in ct by 0.00003149460888, or divide it by 31751.4659. For example, 15 ct × 0.00003149460888 = 0.0004724191333 st.
Is the ct to st conversion exact?
Yes. Both units are defined exactly, so the ratio is exact; its decimal form does not terminate and is shown here to 10 significant figures (more with the precision selector).
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".
- 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, pound (avoirdupois).
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 Stone. Retrieved October 17, 2026, from https://scientificconverters.com/mass/carats-to-stone/
IEEE
Scientific Converters, "Convert Carats to Stone," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/mass/carats-to-stone/