Understanding Carats to Troy ounces Conversion
The metric carat (ct) is a unit of mass equal to exactly 200 milligrams, used worldwide to weigh gemstones and pearls. The troy ounce (ozt) is 31.1035 grams and is the standard unit for precious metals such as gold and silver. Jewellers and bullion dealers cross this bridge constantly, since gemstones are priced in carats while their precious-metal settings are priced in troy ounces.
Conversion Formula
To convert carats to troy ounces, multiply by this factor:
Step-by-Step Example
Convert 25 carats to troy ounces.
How to Convert Carats to Troy ounces
Convert any carats value into troy ounces in three quick steps.
- Note the carat weight: Take the gemstone or parcel mass in carats (ct).
- Multiply by the factor: Multiply the carat figure by 0.006430149 to convert into troy ounces.
- State the result: The product is the equivalent mass in troy ounces (ozt).
For example, 25 carats equals 0.160754 ozt.
Carats to Troy Ounces conversion table
| Carats (ct) | Troy Ounces (ozt) |
|---|---|
| 0 | 0 |
| 1 | 0.006430149 |
| 2 | 0.0128603 |
| 3 | 0.01929045 |
| 4 | 0.0257206 |
| 5 | 0.03215075 |
| 6 | 0.0385809 |
| 7 | 0.04501105 |
| 8 | 0.05144119 |
| 9 | 0.05787134 |
| 10 | 0.06430149 |
| 15 | 0.09645224 |
| 20 | 0.128603 |
| 25 | 0.1607537 |
| 30 | 0.1929045 |
| 40 | 0.257206 |
| 50 | 0.3215075 |
| 60 | 0.385809 |
| 70 | 0.4501105 |
| 80 | 0.5144119 |
| 90 | 0.5787134 |
| 100 | 0.6430149 |
| 150 | 0.9645224 |
| 200 | 1.28603 |
| 250 | 1.607537 |
| 300 | 1.929045 |
| 400 | 2.57206 |
| 500 | 3.215075 |
| 600 | 3.85809 |
| 700 | 4.501105 |
| 800 | 5.144119 |
| 900 | 5.787134 |
| 1000 | 6.430149 |
| 2000 | 12.8603 |
| 3000 | 19.29045 |
| 4000 | 25.7206 |
| 5000 | 32.15075 |
| 10000 | 64.30149 |
| 25000 | 160.7537 |
| 50000 | 321.5075 |
| 100000 | 643.0149 |
| 250000 | 1607.537 |
| 500000 | 3215.075 |
| 1000000 | 6430.149 |
What is the Carat?
The carat is a unit of mass used to weigh gemstones and pearls. It should not be confused with the "karat," which measures gold purity.
Definition
The metric carat is defined as exactly 200 milligrams:
That is, 1 carat = 200 mg = 0.2 g exactly. Each carat is further divided into 100 "points," so a 0.25 ct stone is called a 25-point diamond.
Origin and History
The word derives from the carob seed (Greek keration), historically used as a counterweight in balancing scales because its mass was thought to be remarkably consistent. To end regional variation, the metric carat of exactly 200 mg was adopted internationally in the early 20th century, around 1907–1914.
Law and Notable Facts
The metric carat is legally recognized in most countries for the gem trade. A common misconception is that carat measures a diamond's size; it actually measures mass, so two stones of equal carat can look different depending on cut and shape.
Real-World Examples and Conversions
A typical engagement-ring diamond is around 1 carat (200 mg). The Hope Diamond weighs about 45.52 carats (≈9.10 g). Five carats equal exactly one gram.
What is the Troy Ounce?
The troy ounce is a unit of mass used almost exclusively for precious metals such as gold, silver, platinum, and palladium. It is the standard weight quoted on global bullion markets.
Definition
The troy ounce is defined as exactly 480 grains, which equals 31.1034768 grams:
By definition, 1 troy ounce = 480 grains = 31.1034768 g exactly, and 12 troy ounces make one troy pound (≈373.242 g). Note that the troy ounce is heavier than the more familiar avoirdupois ounce (≈28.3495 g).
Origin and History
The troy system takes its name from the French market town of Troyes, a major medieval trading hub. It descends from the Roman monetary system and was standardized in England for coinage and precious metals, later adopted across Europe and the English-speaking world.
Law and Notable Facts
The troy ounce remains the legal basis for bullion trading and coinage weights; in the United States it is codified for precious-metal transactions. A curious consequence is that a pound of gold (troy, ~373 g) actually weighs less than a pound of feathers (avoirdupois, ~454 g).
Real-World Examples and Conversions
A standard Good Delivery gold bar weighs about 400 troy ounces (≈12.4 kg). A 1 oz American Gold Eagle contains one troy ounce (31.1 g) of gold. When gold is quoted at "$2,000 per ounce," that means per troy ounce, not the avoirdupois ounce.
Frequently Asked Questions
What is a carat?
A metric carat is exactly 200 milligrams, the international standard for weighing gemstones and pearls; it is unrelated to karat, which measures gold purity.
How many troy ounces is one carat?
One carat equals about 0.006430149 troy ounces.
Why do jewellers need carats and troy ounces?
Gemstones are weighed in carats but the gold or silver holding them is weighed in troy ounces, so both units appear on the same invoice.
How do I convert carats to troy ounces?
Multiply the carat value by 0.006430149 to obtain troy ounces.
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Complete Carats conversion table
| Unit | Result |
|---|---|
| Micrograms (mcg) | 200000 mcg |
| Milligrams (mg) | 200 mg |
| Grams (g) | 0.2 g |
| Kilograms (kg) | 0.0002 kg |
| Metric Tonnes (mt) | 2e-7 mt |
| Ounces (oz) | 0.007054792 oz |
| Pounds (lb) | 0.0004409245 lb |
| Stones (st) | 0.00003149461 st |
| Tons (t) | 2.204623e-7 t |
| Long Tons (long-ton) | 1.968413e-7 long-ton |
| Troy Ounces (ozt) | 0.006430149 ozt |
| Grains (gr) | 3.086472 gr |
| US Hundredweights (cwt-us) | 0.000004409245 cwt-us |
| UK Hundredweights (cwt-uk) | 0.000003936826 cwt-uk |
| Slugs (slug) | 0.00001370435 slug |