How many carats are in one ounce?

One avoirdupois ounce equals approximately 141.748 carats. Each carat is defined as exactly 0.2 grams, and one ounce is about 28.3495 grams, so dividing gives the conversion factor.

Is the carat used for measuring anything other than gemstones?

The metric carat is used almost exclusively for gemstones and pearls. However, the word 'karat' (spelled with a K) refers to gold purity, where 24 karat means pure gold. These are entirely different measurements despite their shared etymology.

Why is the carat exactly 0.2 grams?

The metric carat was standardized at 200 milligrams (0.2 grams) in 1907 by the Fourth General Conference on Weights and Measures. Before standardization, the carat varied by region, originally based on the weight of carob seeds, which were believed to have remarkably consistent mass.

Ounces to Carats (oz to ct) Converter

1 oz = 141.7476 ct

1 Ounce equals 141.7476 Carats (1 oz = 141.7476 ct). Convert Ounces to Carats with formula, table, and examples.

One avoirdupois ounce equals approximately 141.748 carats. The carat is the standard unit for gemstone and diamond weight, fixed internationally at exactly 0.2 grams, while the ounce remains a cornerstone of daily weight measurement in the United States and United Kingdom.

How to Convert Ounces to Carats

ct = oz × 141.747615625

Multiply the value in Ounces by 141.747615625

Take your value in Ounces
Multiply by 141.747615625
Read the result in Carats

Common Ounces to Carats Conversions

Ounces (oz)	Carats (ct)	Status
1 oz	141.748 ct
2 oz	283.495 ct
5 oz	708.738 ct
10 oz	1,417.476 ct
25 oz	3,543.69 ct
50 oz	7,087.381 ct
100 oz	14,174.762 ct
500 oz	70,873.808 ct
1,000 oz	141,747.616 ct

Good to Know About Ounces to Carats Conversion

The word 'carat' traces back to the Greek 'keration,' referring to the carob seed, which Mediterranean merchants used as a counterweight on balance scales because they believed each seed had nearly identical mass. Modern research has shown that carob seeds actually vary by about 5 percent, making them far less reliable than the legend suggests.

Ounces to Carats: What You Need to Know

A typical engagement ring diamond weighs between 0.5 and 1.5 carats, meaning you would need roughly 95 to 283 such stones to equal one ounce. Gemstone dealers routinely convert between ounces and carats when purchasing rough stones in bulk, particularly at international trading hubs like Antwerp, Mumbai, and Tel Aviv. Gold bullion, though traded in troy ounces, often accompanies gemstone transactions where carat weight determines the centerpiece value.

What is a Ounce? oz

An imperial and US customary unit of mass equal to approximately 28.35 grams. Commonly used in the US and UK for food and postal weight.

Imperial Us-customary food packaging (US/UK) postal weight cooking (US)

Learn more about Ounce →

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 →

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

Ounces to Carats FAQ

One avoirdupois ounce equals approximately 141.748 carats. Each carat is defined as exactly 0.2 grams, and one ounce is about 28.3495 grams, so dividing gives the conversion factor.
The metric carat is used almost exclusively for gemstones and pearls. However, the word 'karat' (spelled with a K) refers to gold purity, where 24 karat means pure gold. These are entirely different measurements despite their shared etymology.
The metric carat was standardized at 200 milligrams (0.2 grams) in 1907 by the Fourth General Conference on Weights and Measures. Before standardization, the carat varied by region, originally based on the weight of carob seeds, which were believed to have remarkably consistent mass.

Non-Frequently Asked Questions About Ounces to Carats

Questions nobody should ask - but someone did.

Technically, a 6-ounce sandwich clocks in at about 850 carats. You could say you are eating an 850-carat lunch, but jewelers might be less impressed when they realize the gem in question is turkey on rye.
A 1-carat diamond weighs 0.007 ounces, roughly the weight of a small crumb of cheddar. The diamond, however, costs considerably more per crumb. The cheese market and the diamond market have not yet merged, despite both involving aging and careful cutting.
An average house cat weighing about 10 pounds (160 ounces) comes in at roughly 22,680 carats. That makes your tabby more carats than most crown jewels combined, though admittedly less sparkly and considerably less cooperative during appraisal.