Ounces to grams: how many grams in an ounce?
28.35 grams in an ordinary ounce, 31.1035 grams in a troy ounce. Gold and silver are always weighed in troy ounces.
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The short answer
1 ounce = 28.3495 grams. 1 troy ounce = 31.1035 grams. If you are weighing gold, silver or platinum, use the troy ounce: it is the unit behind every price quoted per ounce.
Troy ounces to grams
| Troy ounces | Grams |
|---|---|
| 1/10 troy ounce | 3.110 g |
| 1/4 troy ounce | 7.776 g |
| 1/2 troy ounce | 15.552 g |
| 1 troy ounce | 31.1035 g |
| 5 troy ounces | 155.517 g |
| 10 troy ounces | 311.035 g |
| 32.1507 troy ounces | 1,000 g (1 kilogram) |
| 100 troy ounces | 3,110.35 g |
| 400 troy ounces | 12,441.4 g (a Good Delivery gold bar) |
Troy ounce vs ounce
The troy ounce comes from the medieval troy weight system and survives only for precious metals and gemstones. It is divided into 20 pennyweights, and 12 troy ounces make a troy pound. The ordinary ounce belongs to the avoirdupois system, where 16 ounces make a pound. Weigh gold on kitchen scales set to ounces and you will read about 10% too many.
Weighing gold and silver at home
Set your scales to grams, which avoids the confusion altogether. Weigh pieces of the same carat together, and remember that stones, springs and watch movements add weight that is not metal.
See the live gold price and the live silver price, or check UK coin weights.
Weight converter
- Grams
- 31.1035
- Ounces
- 1.0971
- Kilograms
- 0.0311
- Pounds
- 0.0686
- Pennyweights
- 20
- Tolas
- 2.6667
Gold, silver and platinum are weighed in troy ounces. A troy ounce is 31.1035 grams; an ordinary ounce is 28.3495 grams.
A free valuation from your photographs
Send a few photos and the weight if you know it. A specialist replies within one working day, and antique or signed pieces are valued as more than metal.
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Ounces and grams: questions
How many grams are in an ounce?
An ordinary (avoirdupois) ounce is 28.3495 grams. A troy ounce, the unit used for gold, silver and platinum, is 31.1035 grams.
How many grams are in a troy ounce?
One troy ounce is exactly 31.1034768 grams. Gold and silver prices quoted per ounce always mean a troy ounce.
What is the difference between a troy ounce and an ounce?
A troy ounce is about 10% heavier: 31.1035 grams against 28.3495 grams. Precious metals use troy ounces; food and post use ordinary ounces.
How many ounces are in a gram?
One gram is 0.03215 troy ounces, or 0.03527 ordinary ounces.
How many troy ounces are in a kilogram?
There are 32.1507 troy ounces in one kilogram.
How many grams are in a pennyweight?
One pennyweight (dwt) is 1.5552 grams. There are 20 pennyweights in a troy ounce.
How many grams are in a tola?
One tola is 11.6638 grams. It is the traditional unit for gold in India and Pakistan.
Is a one ounce gold coin exactly 31.1 grams?
It contains one troy ounce of fine gold. A 22 carat coin such as a Krugerrand weighs more in total, 33.93 grams, because of the alloy.
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