Carats to Ounces
Convert carats to ounces instantly — one carat is 0.00705479 ounces.
| Carats | Ounces |
|---|---|
| 1 ct | 0.007055 oz |
| 2 ct | 0.01411 oz |
| 3 ct | 0.021164 oz |
| 5 ct | 0.035274 oz |
| 10 ct | 0.070548 oz |
| 25 ct | 0.17637 oz |
| 50 ct | 0.35274 oz |
| 100 ct | 0.705479 oz |
How to use
- Enter a value in the Carats field.
- The Ounces figure appears immediately — no button to press.
- Typing in the Ounces field converts back to Carats the same way.
- Use the reference table for the values that come up most often.
Carats to Ounces formula
The factor from carats to ounces is 0.00705479239.
oz = ct × 0.00705479239
Why this factor: the carat and the ounce are both defined against the kilogram, so dividing one definition by the other gives 0.00705479239 directly. Both definitions are set out in full below.
To go the other way, divide by 0.00705479239 — or use the Ounces to Carats converter, which is the same calculation reversed.
Worked example
Start with 150 ct. Multiply by 0.00705479239 to get 1.058219 oz.
150 ct × 0.00705479239 = 1.058219 oz
The converter above does this for any value you type, in either direction.
What is a carat?
A metric carat is the standard mass unit for gemstones.
Definition: Exactly 200 milligrams — that is, 0.2 gram — standardized internationally in 1907.
Where it is used: Diamond and gemstone weight throughout the jewellery trade.
Worth knowing: Do not confuse the carat (gemstone mass) with the karat (gold purity out of 24). A 1-carat diamond and 24-karat gold measure entirely different things.
What is an ounce?
An ounce is one sixteenth of a pound, used for small weights in the US.
Definition: Exactly 28.349523125 grams — one sixteenth of the international avoirdupois pound.
Where it is used: Food packaging, postal weights, and coffee and spice quantities in the US.
Worth knowing: Not the same as a fluid ounce, which measures volume. Also distinct from the troy ounce (31.103 g) used for gold and silver.
Carats vs Ounces
The carat is a specialized unit while the ounce is an imperial unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many ounces are in a carat?
One carat equals 0.00705479239 ounces.
What is the formula to convert carats to ounces?
Multiply the number of carats by 0.00705479239. To reverse it, divide by 0.00705479239 instead.
How do I convert ounces back to carats?
Divide by 0.00705479239, which is the same as multiplying by 141.747616.
How many ounces are in 10 carats?
10 ct works out to 0.070548 oz.
Is there anything to watch out for with carats?
Do not confuse the carat (gemstone mass) with the karat (gold purity out of 24). A 1-carat diamond and 24-karat gold measure entirely different things.
How is the carat defined?
Exactly 200 milligrams — that is, 0.2 gram — standardized internationally in 1907.