How many centigrams are in one carat?

One carat equals exactly 20 centigrams. This comes from 1 carat being 0.2 grams and 1 centigram being 0.01 grams: 0.2 divided by 0.01 equals 20.

A centigram is one hundredth of a gram (0.01 g). It is a metric unit that sits between the milligram (0.001 g) and the decigram (0.1 g). While rarely used in everyday life, it appears in some scientific and pharmaceutical contexts.

Why is the carat exactly 0.2 grams?

The modern metric carat was standardized at the Fourth General Conference on Weights and Measures in 1907 at exactly 200 milligrams (0.2 grams). This rounded value was chosen to approximate the historical carat, which was based on carob seeds and varied between roughly 189 and 215 milligrams depending on region.

Carats to Centigrams (ct to cg) Converter

1 ct = 20 cg

1 Carat equals 20 Centigrams (1 ct = 20 cg). Convert Carats to Centigrams with formula, table, and examples.

One carat equals exactly 20 centigrams. The carat, standardized at 200 milligrams (0.2 grams) since 1907, converts cleanly to centigrams because a centigram is one hundredth of a gram. This makes the arithmetic straightforward: 0.2 grams multiplied by 100 centigrams per gram equals 20 centigrams per carat.

How to Convert Carats to Centigrams

cg = ct × 20

Multiply the value in Carats by 20

Take your value in Carats
Multiply by 20
Read the result in Centigrams

Common Carats to Centigrams Conversions

Carats (ct)	Centigrams (cg)	Status
0.25 ct	5 cg
0.5 ct	10 cg
1 ct	20 cg
2 ct	40 cg
3 ct	60 cg
5 ct	100 cg
10 ct	200 cg
25 ct	500 cg
50 ct	1,000 cg
100 ct	2,000 cg
250 ct	5,000 cg
500 ct	10,000 cg
1,000 ct	20,000 cg
5,000 ct	100,000 cg

Good to Know About Carats to Centigrams Conversion

The centigram is a product of the metric system's strict decimal logic, but it never gained the traction that the centimeter did in length measurement. In the world of gemstones, the carat's own sub-units (points, where 100 points equal 1 carat) serve the same purpose as centigrams would, making the centigram redundant for jewelers. The gemstone industry essentially invented its own parallel decimal system within the carat.

Carats to Centigrams: What You Need to Know

While jewelers work in carats and laboratory scientists occasionally use centigrams, the two units rarely overlap in daily practice. A 1-carat diamond weighs 20 centigrams, and a 5-carat sapphire weighs 100 centigrams - exactly 1 gram. This conversion is most useful in gemological education and in countries where centigrams still appear in pharmaceutical or chemical documentation.

What is a Carat? ct

A carat is a unit of mass equal to exactly 200 milligrams (0.2 grams), used for measuring gemstones and pearls. Adopted internationally in 1907 by the Fourth General Conference on Weights and Measures.

Metric diamond weight gemstone grading pearl measurement

Learn more about Carat →

What is a Centigram? cg

A centigram is one hundredth of a gram. It is a metric unit rarely used in everyday life but appears in some scientific and educational contexts.

Metric scientific measurement education

Learn more about Centigram →

Going the other way? Use our Centigrams to Carats converter.

Carats to Centigrams FAQ

One carat equals exactly 20 centigrams. This comes from 1 carat being 0.2 grams and 1 centigram being 0.01 grams: 0.2 divided by 0.01 equals 20.
A centigram is one hundredth of a gram (0.01 g). It is a metric unit that sits between the milligram (0.001 g) and the decigram (0.1 g). While rarely used in everyday life, it appears in some scientific and pharmaceutical contexts.
The modern metric carat was standardized at the Fourth General Conference on Weights and Measures in 1907 at exactly 200 milligrams (0.2 grams). This rounded value was chosen to approximate the historical carat, which was based on carob seeds and varied between roughly 189 and 215 milligrams depending on region.

Non-Frequently Asked Questions About Carats to Centigrams

Questions nobody should ask - but someone did.

A standard cup of black coffee weighs about 237 grams or 23,700 centigrams. That is 1,185 carats. If your morning brew were made of diamonds instead of beans, you would be drinking roughly 12 million dollars worth of coffee. The flavor would probably be worse.
If a customer thought a 20-centigram diamond was a 20-carat diamond, they would expect a stone roughly the size of a walnut - one of the largest diamonds ever found. The actual 20-centigram stone is a modest 1-carat gem. The ensuing price discussion would be memorable.
The centigram shares the obscurity podium with the decigram, decameter, and hectometer. You will almost never see centigrams on a kitchen scale, in a recipe, or at a doctor's office. It exists because the metric system is relentlessly systematic, not because anyone particularly asked for it.