How many carats are in one kilogram?

One kilogram equals exactly 5,000 carats. This comes from 1 carat being exactly 0.2 grams and 1 kilogram being 1,000 grams: 1,000 divided by 0.2 equals 5,000.

Why do gemstone traders need the kilogram conversion?

International shipping, customs duties, and insurance policies require weight in kilograms. A gem dealer might describe inventory as '2,500 carats of sapphire' internally, but customs paperwork needs '0.5 kg' for tariff calculations and freight pricing.

What is the heaviest diamond ever found in kilograms?

The Cullinan Diamond, found in South Africa in 1905, weighed 3,106.75 carats or about 0.621 kg. It was cut into several major gems, the largest being the Great Star of Africa (530.2 carats, about 0.106 kg), which is set in the British Sovereign's Sceptre.

Carats to Kilograms (ct to kg) Converter

1 ct = 0.0002 kg

1 Carat equals 0.0002 Kilograms (1 ct = 0.0002 kg). Convert Carats to Kilograms with formula, table, and examples.

One carat equals exactly 0.0002 kilograms (two ten-thousandths of a kilogram). The kilogram is the base unit of mass in the International System of Units, while the carat is a specialized gemstone unit. At 5,000 carats per kilogram, this conversion is essential for gemstone trade logistics, customs declarations, and insurance valuations where standard metric weight is required.

How to Convert Carats to Kilograms

kg = ct ÷ 5,000

Divide the value in Carats by 5,000

Take your value in Carats
Divide by 5,000
Read the result in Kilograms

Common Carats to Kilograms Conversions

Carats (ct)	Kilograms (kg)	Status
1 ct	0.0002 kg
5 ct	0.001 kg
10 ct	0.002 kg
50 ct	0.01 kg
100 ct	0.02 kg
500 ct	0.1 kg
1,000 ct	0.2 kg
2,500 ct	0.5 kg
5,000 ct	1 kg
10,000 ct	2 kg
25,000 ct	5 kg
50,000 ct	10 kg
100,000 ct	20 kg
500,000 ct	100 kg

Good to Know About Carats to Kilograms Conversion

The kilogram was redefined in 2019 based on the Planck constant, replacing the physical platinum-iridium cylinder that had served as the standard since 1889. This change had no practical effect on the carat-to-kilogram conversion, but it meant that for the first time in history, both units - the carat (defined metrically since 1907) and the kilogram - are based on fundamental physical constants rather than physical artifacts.

Carats to Kilograms: What You Need to Know

The Cullinan Diamond, the largest gem-quality rough diamond ever found, weighed 3,106.75 carats - just 0.621 kilograms, barely more than half a kilogram. Even the most spectacular diamonds are remarkably light in kilogram terms. A wholesale gemstone dealer might handle hundreds of thousands of carats annually, but the total physical weight in kilograms would fit in a few small bags.

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 Kilogram? kg

The base unit of mass in the International System of Units (SI). Equal to 1000 grams. Used worldwide for everyday weighing and commerce.

Metric everyday weighing commerce medicine

Learn more about Kilogram →

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

Carats to Kilograms FAQ

One kilogram equals exactly 5,000 carats. This comes from 1 carat being exactly 0.2 grams and 1 kilogram being 1,000 grams: 1,000 divided by 0.2 equals 5,000.
International shipping, customs duties, and insurance policies require weight in kilograms. A gem dealer might describe inventory as '2,500 carats of sapphire' internally, but customs paperwork needs '0.5 kg' for tariff calculations and freight pricing.
The Cullinan Diamond, found in South Africa in 1905, weighed 3,106.75 carats or about 0.621 kg. It was cut into several major gems, the largest being the Great Star of Africa (530.2 carats, about 0.106 kg), which is set in the British Sovereign's Sceptre.

Non-Frequently Asked Questions About Carats to Kilograms

Questions nobody should ask - but someone did.

One kilogram is 5,000 carats. The price depends wildly on quality: 5,000 carats of industrial-grade diamonds might cost a few hundred thousand dollars, while 5,000 carats of flawless D-color brilliant-cut stones would be worth billions - far more than anyone has ever assembled in one place.
One million carats equals exactly 200 kilograms. That is roughly the weight of a large refrigerator. You could not carry it, but you could roll it on a cart. At even modest quality, this cart would be worth more than most countries' GDP. You would want very good insurance and a very strong lock.
Yes, both weigh exactly one kilogram. But the diamonds would occupy much less space because diamond has a density of about 3.52 g/cm cubed, while feathers are mostly air. A kilogram of loose feathers would fill a large pillow; a kilogram of diamonds would fit in a coffee mug.