Convert Ounces to Carats

About converting Ounces to Carats

Ounces (oz) and Carats (ct) are both units of weight & mass, so converting between them is a single multiplication: multiply your Ounces figure by 141.7476. Ten Ounces comes to 1,417.48 Carats, and a hundred works out at 14,174.76 Carats.

Rule of thumb: going from Ounces to Carats multiplies, so the figure always grows — one Ounce is already 141.7476 Carats. If your answer came out smaller, you have the conversion the wrong way round.

What is an Ounce?

The ounce here is the avoirdupois ounce, one sixteenth of a pound, and the qualifier matters. The troy ounce used to price gold and silver is noticeably heavier, so a "one ounce" gold coin is not an ounce of anything else — a confusion that has cost people real money. Muddier still is the fluid ounce, which measures volume rather than mass and differs between the US and the UK. The name comes from the Latin uncia, a twelfth part: it was a twelfth of the Roman libra, and the move to sixteen ounces to the pound came later.

What is a Carat?

The metric carat is 0.2 grams exactly, standardised early in the twentieth century to replace a tangle of local carats that differed from one gem market to the next. Its name is traditionally traced to the carob seed, once used as a counterweight for small valuables. The trap is the near-identical karat, which is not a mass at all — it measures gold purity in twenty-fourths, so 18-karat gold is eighteen parts gold to six of other metal. Jewellers also split the carat into 100 points, which is why a "fifty-point" diamond is simply half a carat.

To put both in perspective: a slice of sandwich bread weighs about an ounce, while a typical engagement-ring diamond weighs about one carat.

The converter above updates as you type, and the table lists common values for quick reference. Need the opposite direction? Use the Carats to Ounces converter, or browse all Weight & Mass converters.