How to convert carats to stone
To convert a measurement in carats to stone, multiply the value by 0.000031494609. The conversion factor comes from the relationship between both units and the kilogram.
For example, to convert 5 ct to stone: 5 × 0.000031494609 = 0.000157473044 st.
What is a carat?
A carat is a unit of mass for gemstones equal to exactly 200 milligrams (0.2 grams). The carat takes its name from the carob seed, once used as a counterweight for weighing gems. The metric carat of exactly 200 mg was adopted internationally in the early 20th century to standardize the gem trade.
Common uses of carats include: Diamond and gemstone weight; Jewelry pricing and grading; Pearl and precious stone trading; Gemological certification.
What is a stone?
A stone is a British imperial unit of mass equal to 14 pounds or exactly 6.35029318 kilograms. The stone was historically used across Europe with regionally varying values before Britain standardized it at 14 pounds. It remains in everyday use in the UK and Ireland for body weight despite metrication.
Common uses of stone include: Body weight in the UK and Ireland; Weigh-ins for sports and fitness in Britain; Historical and livestock weight references; Everyday conversational weight in the British Isles.
Carats to stone worked examples
Here are some common values converted:
1 ct = 0.000031494609 st 5 ct = 0.000157473044 st 10 ct = 0.000314946089 st 50 ct = 0.001574730444 st 100 ct = 0.003149460888 st
Frequently asked questions
How many stone are in one carat?
One carat (ct) equals 0.000031494609 stone (st). Multiply any value in carats by 0.000031494609 to convert to stone.
How do I convert carats to stone?
Multiply the value in carats by 0.000031494609. For example, 5 ct × 0.000031494609 = 0.000157473044 st.
How do I convert stone to carats?
Multiply the value in stone by 31,751.4659, or divide by 0.000031494609. Use the swap button on the converter above to reverse the direction.
Is the carat to stone conversion exact?
Yes. Since 1959 the international pound is defined as exactly 0.45359237 kg, so all weight conversions between metric and avoirdupois units use exact factors.
What is the formula for carats to stone?
The formula is: st = ct × 0.000031494609. This comes from the definition of both units relative to the kilogram.