How Many Grams in a Troy Ounce?
31.1 g
There are 31.1 grams in 1 troy ounce.
Exact: 1 oz t = 31.1034768 g
Troy Ounces to Grams conversion chart
| Troy Ounces | Grams |
|---|---|
| 0.1 oz t | 3.11 |
| 0.25 oz t | 7.776 |
| 0.5 oz t | 15.55 |
| 1 oz t | 31.1 |
| 2 oz t | 62.21 |
| 3 oz t | 93.31 |
| 4 oz t | 124.4 |
| 5 oz t | 155.5 |
| 10 oz t | 311 |
| 15 oz t | 466.6 |
| 20 oz t | 622.1 |
| 25 oz t | 777.6 |
| 32.15 oz t | 1,000 |
| 50 oz t | 1,555 |
| 100 oz t | 3,110 |
| 400 oz t | 12,441 |
| 1,000 oz t | 31,103 |
How to convert troy ounces to grams
grams = troy ounces × 31.1035
Example: 5 oz t × 31.1035 = 155.5 g.
Multiply the troy ounces by 31.1035, or by the full 31.1034768 when you need every digit. Either way, round only the final answer.
For everyday amounts, 31.1 is close enough: 20 oz t comes to 622 g either way. Keep the longer factor for big totals, because the dropped digits add up. 400 oz t is 12,441 g, or 12.44 kg.
To turn grams back into troy ounces, divide by the same factor or use grams to troy ounces.
Converting fractional coin sizes to grams
Gold coins also come in fractions of a troy ounce. US law, for example, defines American Eagle gold coins that hold one-half, one-quarter and one-tenth of a troy ounce of fine gold (31 U.S.C. 5112).
In grams of pure gold, those sizes work out to 15.55 g, 7.776 g and 3.11 g. The figures describe the gold inside, not the whole coin, which also contains a little alloy.
A scale that reads to one decimal place of a gram can tell these sizes apart. It cannot confirm purity, so treat a weighing as a rough check only.
Troy Ounces and grams: questions
Why is an ounce of gold 31 grams?
Because gold is weighed in troy ounces, which are heavier than the 28.35 g ounce on a kitchen scale. Both ounces are built from the same tiny unit, the grain, but the troy ounce holds more grains (NIST Handbook 44). The troy system is kept for precious metals, so an ounce of gold means a troy ounce.
Is an ounce 28 or 32 grams?
Neither, exactly. A regular ounce is 28.35 g and a troy ounce is 31.1 g, so the answer depends on which ounce you mean. No standard ounce weighs 32 grams, so treat that number as a rounding slip.
What does 1 oz of gold weigh?
A troy ounce of pure gold weighs 31.1 g, not the 28.35 g of a kitchen ounce. A coin sold as one ounce can weigh more in total: US law sets the one-ounce American Eagle, a fifty-dollar gold coin, at about 33.93 g, because its troy ounce of gold is mixed with a little alloy.
Is a troy ounce the same for gold, silver and platinum?
Yes. The troy ounce is a unit of weight, so it does not change from one metal to the next. Only the size of the piece changes: a denser metal packs the same weight into less space, so a gold coin is smaller than a silver coin of the same weight.
How many troy ounces are in a kilogram?
A kilogram holds 32.15 oz t, and 100 g holds 3.215 oz t. Metric bars and ounce coins can be compared this way, as long as both figures refer to pure metal.
Related conversions
Sources: Unit definitions: NIST Handbook 44 · Last reviewed · Report an error
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