Carats to Ounces (ct to oz)

1 carat equals 0.00705479239 ounces (rounded).

1 carat = 0.00705479239 ounces

How to convert carats to ounces

To convert carats to ounces, multiply the number of carats by 0.00705479239. The factor is rounded to 10 significant digits. To go the other way, multiply ounces by 141.7476156 (rounded).

ounces = carats × 0.00705479239

Example: 10 carats = 0.0705479239 ounces.

About these units

Carat (ct)

Metric (SI)Current unit

Exactly 200 milligrams. The unit for weighing gemstones such as diamonds. Not to be confused with the karat, a measure of gold purity.

Jewellers once weighed stones against seeds. The word carat traces back to the Greek keration, meaning a carob seed, and reached English through Italian and Arabic. Carob seeds were used as balance weights for gems and gold, though their mass varies about as much as any seed does. Before 1907 each country had its own carat, ranging from roughly 187 to 216 milligrams. It was used for gold early on and for diamonds from the 1570s. An international carat of 205 mg was proposed in Paris in 1871, but the 200 mg metric carat won out.

The metric carat was adopted at the Fourth General Conference on Weights and Measures in 1907. France made it mandatory, the United States followed in 1913 and the United Kingdom in 1914. Today it is exactly 200 mg, so five carats make a gram, and it is divided into 100 points of 2 mg each; a diamond described as 25 points is a quarter carat. Carat is used for gemstones and pearls, and it should not be mixed up with karat, which measures the purity of gold and is a separate idea.

1 carat = 0.0002 kilograms (exactly).

Sources: Wikipedia: Carat (mass); NIST Guide to the SI, Appendix B.8 (mass conversions)

Ounce (oz)

US & ImperialCurrent unit

One sixteenth of a pound, exactly 28.349523125 g. Used for food, mail and consumer goods in the US and UK.

A twelfth part is what ounce originally meant. It comes from the Roman uncia, one twelfth of the Roman pound, a word that also gave English the inch. The abbreviation oz does not come from English at all but from the Italian onza or oncia. Over the centuries many regions and trades used different ounces: the English Tower ounce of 29.16 g was abolished by Henry VIII in 1527, and the Dutch ons was redefined as exactly 100 g in 1820.

The avoirdupois ounce used for everyday goods is one sixteenth of a pound, exactly 28.349523125 g or 437.5 grains, the standard in the US and under the UK imperial system. It is not the same as the troy ounce for precious metals, and neither is the fluid ounce, which measures volume. Ounces still describe portions such as steaks and burgers, and they show up in unexpected places: fabric is graded by weight per area, so a 16 oz denim is a heavy cloth, and the copper on a circuit board is specified in ounces, where 1 oz is roughly 34.7 micrometres thick.

1 ounce = 0.02834952313 kilograms (approximately).

Sources: Wikipedia: Ounce; NIST Guide to the SI, Appendix B.8 (mass conversions)

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