Precious-metals reference
How Many Grams Are in an Ounce? Troy vs Standard Ounces
One troy ounce is 31.1034768 grams. One standard ounce is 28.349523125 grams. Gold, silver, platinum and palladium are normally weighed in troy ounces.
Weight converter
Convert grams and ounces
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Result
31.1034768 grams
1 troy ounce equals 31.1034768 grams.
Quick answer
Troy ounces are heavier than standard ounces
A standard ounce, also called an avoirdupois ounce, is 28.349523125 grams. A troy ounce is 31.1034768 grams. The troy ounce is therefore 2.753953675 grams, or about 9.7%, heavier.
Precious metals normally use troy ounces. If a gold bar or bullion coin is described as one ounce, that normally refers to one troy ounce of fine metal rather than the standard ounce used for many everyday goods.
Visual comparison
A troy ounce contains more grams
Reference table
Exact ounce and gram conversions
| Unit | Equivalent | Typical use |
|---|---|---|
| 1 troy ounce | 31.1034768 grams | Gold, silver, platinum and palladium |
| 1 standard ounce | 28.349523125 grams | Everyday goods and general weight |
| Difference | 2.753953675 grams | Troy ounce minus standard ounce |
| 1 kilogram | 32.15074657 troy ounces | Large precious-metal weights |
| 1 pennyweight | 1.55517384 grams | Jewellery and precious metals |
| 1 troy ounce | 20 pennyweight | Troy-weight relationship |
The formula
How to convert grams and troy ounces
Troy ounces = grams ÷ 31.1034768
Grams = troy ounces × 31.1034768
The converter normalises every unit through its exact gram factor and rounds only the displayed result.
Bullion reference
Common fractional troy-ounce weights
| Troy-ounce fraction | Fine-metal weight |
|---|---|
| 1/20 oz t | 1.55517384 grams |
| 1/10 oz t | 3.11034768 grams |
| 1/4 oz t | 7.7758692 grams |
| 1/2 oz t | 15.5517384 grams |
| 1 oz t | 31.1034768 grams |
These figures describe fine-metal weight. A coin's gross weight can be higher when its alloy contains another metal.
Important distinction
Fine-metal weight and gross weight are different
A coin described as containing one troy ounce of fine gold contains 31.1034768 grams of pure gold. The entire coin can weigh more if the metal is alloyed for colour or durability.
Always check the issuing mint's specification when you need the gross weight of a particular coin.
Purity
Does carat change the conversion?
No. A troy ounce always equals 31.1034768 grams. Carat or fineness changes the proportion of fine gold inside the total weight; it does not change the unit conversion.
Frequently asked questions
Grams and ounces: common questions
How many grams are in an ounce of gold?
One troy ounce of gold is 31.1034768 grams. Precious metals normally use the troy ounce rather than the 28.349523125-gram standard ounce.
Is a troy ounce heavier than a normal ounce?
Yes. A troy ounce is 2.753953675 grams heavier than a standard ounce.
How many troy ounces are in one kilogram?
One kilogram is approximately 32.15074657 troy ounces.
Is a one-ounce gold coin always 31.1034768g in total?
Not necessarily. It may contain 31.1034768g of fine gold but have a higher gross weight because of its alloy. Check the mint's specification.
Can this converter tell me what my gold is worth?
No. It converts mass only. Value depends on price, confirmed metal, purity, net weight and the valuation route.
How many grams are in half a troy ounce?
Half a troy ounce is 15.5517384 grams. A quarter troy ounce is 7.7758692 grams.
What does dwt mean in precious-metal weights?
Dwt means pennyweight. One pennyweight is 1.55517384 grams, and 20 pennyweight equal one troy ounce.
Methodology
Sources and calculation standard
This converter uses published measurement and precious-metals conversion standards. It calculates through exact gram constants, uses the exact ounce ratio where appropriate, and rounds only the visible result.
Prepared and fact-checked for review by the London Gold Centre precious-metals team · 10 September 2026
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