21 Carat to Kilogram
Quick answer
21 Carat (ct) equals
0.0042 kg
To convert 21 Carats to Kilograms, multiply by 0.0002. Therefore, 21 Carat (ct) equals 0.0042 Kilogram (kg).
Formula: kg = ct × 0.0002. Calculation: 21 × 0.0002 = 0.0042 kg.
Convert Carat (ct) to Kilogram (kg) online with our free unit converter. In mass, 1 ct = 0.0002 kg. Explore step-by-step conversion steps, mathematical formulas, and quick conversion reference tables below.
Worked example: converting Carat to Kilogram
- Step 1 — start with the formula. kg = ct × 0.0002
- Step 2 — substitute your figure. 21 ct × 0.0002
- Step 3 — read the result. 21 ct = 0.0042 kg
- Step 4 — check it in reverse. ct = kg × 5,000 returns 21 ct, which matches the figure you started with.
Mass Converter
26 units available
21 ct = 0.0042 kg
Formula:
kg = ct × 0.0002With your value: 21 ct = 0.0042 kg
How big is that?
Everyday references on a logarithmic scale, all expressed in carat so you can sanity-check the result.
Other Carat to Kilogram conversions
Carat to Kilogram Conversion Table
| Carat (ct) | Kilogram (kg) |
|---|---|
| 0.5 | 0.0001 |
| 1 | 0.0002 |
| 2 | 0.0004 |
| 5 | 0.001 |
| 10 | 0.002 |
| 15 | 0.003 |
| 20 | 0.004 |
| 25 | 0.005 |
| 50 | 0.01 |
| 100 | 0.02 |
| 250 | 0.05 |
| 500 | 0.1 |
| 1000 | 0.2 |
Kilogram to Carat Conversion Table
| Kilogram (kg) | Carat (ct) |
|---|---|
| 0.5 | 2,500 |
| 1 | 5,000 |
| 2 | 10,000 |
| 5 | 25,000 |
| 10 | 50,000 |
| 15 | 75,000 |
| 20 | 100,000 |
| 25 | 125,000 |
| 50 | 250,000 |
| 100 | 500,000 |
| 250 | 1,250,000 |
| 500 | 2,500,000 |
| 1000 | 5,000,000 |
Where these values come from
Every factor on this page is traced to the document that defines it. See the full provenance dataset or our methodology.
Carat (ct)
Mass
The metric carat is exactly 200 mg, agreed internationally in 1907.
National Institute of Standards and Technology (US) · Reviewed 2026-07-01
Kilogram (kg)
Mass
The kilogram is defined by taking the Planck constant to be exactly 6.626 070 15 × 10⁻³⁴ J·s.
Source: BIPM, The International System of Units (SI), 9th edition, 2019 (updated 2024)
Bureau International des Poids et Mesures · Reviewed 2026-07-01
How to Convert Carat to Kilogram
To convert from Carat (ct) to Kilogram (kg), multiply the value by 0.0002.
Formula: kg = ct × 0.0002
Reverse: ct = kg × 5,000
Step-by-Step Example
- Start with your value in Carat. For example: 5 ct
- Multiply by the conversion factor: 5 x 0.0002
- The result is: 0.001 kg
Carat and Kilogram Relationship
This calculation facilitates standardized conversion between recognized units of mass. Since 1 Carat represents a fraction of a Kilogram (1 Kilogram ≈ 5,000 Carats), the Kilogram is the larger measurement interval. Understanding the relationship between Carat and Kilogram is essential for accurate calculations in physics, engineering, commerce, and daily applications.
About Carat
The carat equals 200 milligrams and is the standard unit for measuring gemstone weight.
Fun Fact: The word "carat" comes from the carob seed, which was used as a balance weight in ancient gem trading.
Common uses of Carat: gemstones, diamonds, jewelry.
About Kilogram
The kilogram is the base unit of mass in the SI system. Since 2019, it is defined by the Planck constant rather than a physical artifact.
Fun Fact: Until 2019, the kilogram was defined by a platinum-iridium cylinder kept in Paris, called "Le Grand K."
Common uses of Kilogram: body weight, cooking, shipping.
Frequently Asked Questions
- What is 21 Carat in Kilogram?
- 21 Carat equals 0.0042 Kilogram.
- How many Kilograms are in 1 Carat?
- There are exactly 0.0002 Kilograms in 1 Carat. This means the conversion factor from Carat to Kilogram is 0.0002.
- What is the formula to convert Carat to Kilogram?
- The formula to convert Carat to Kilogram is: kg = ct × 0.0002. For example, to convert 10 Carats to Kilograms, you would multiply 10 by 0.0002.
- What is a Carat?
- The carat equals 200 milligrams and is the standard unit for measuring gemstone weight.
- What is a Kilogram?
- The kilogram is the base unit of mass in the SI system. Since 2019, it is defined by the Planck constant rather than a physical artifact.
- What are the common uses of Carat?
- The Carat is commonly used in gemstones, diamonds, jewelry.
Related Mass Conversions
Cite this page
UnitConvertLab. (2026). 21 Carat to Kilogram. UnitConvertLab. Retrieved from https://unitconvertlab.com/convert/21-carat-to-kilogram