About the Troy Ounces to Grams
This troy ounces to grams converter translates precious-metal weights between troy ounces, grams, kilograms, pennyweights, grains, troy pounds, ordinary (avoirdupois) ounces and tola. Choose the unit you are starting from — a 1 oz coin, a 100 g bar, a 1 kg bar or a jeweller’s pennyweight — and every equivalent is shown, with the headline answer in grams or troy ounces.
Gold, silver, platinum and palladium prices are quoted per troy ounce, while bars and jewellery are often weighed in grams. Converting accurately lets investors compare the price per gram of different products, check a dealer’s weight, or value scrap jewellery.
A troy ounce is exactly 31.1034768 g — about 9.7% heavier than the 28.35 g ounce used for food. Mixing the two is a common and costly mistake, so the avoirdupois ounce is listed separately for comparison. The tool converts weight only; multiply by a current spot price for value.
How to use the troy ounces to grams
- 1Enter the weight you want to convert.
- 2Choose its unit — troy ounces, grams, kilograms, pennyweights and so on.
- 3Read the headline answer in grams (or in troy ounces if you started from another unit).
- 4Check every other unit in the results and the troy-ounce chart below.
Formula and method
The troy ounce is defined as 480 grains, and a grain is exactly 64.79891 mg, so 1 troy ounce = 480 × 0.06479891 = 31.1034768 g. The converter changes your value into grams using the size of the chosen unit and then divides by the size of each other unit.
In the troy system 1 troy pound = 12 troy ounces and 1 troy ounce = 20 pennyweights. The avoirdupois ounce (28.349523125 g) is shown only for comparison, and the tola (11.6638038 g, 180 grains) is the traditional South Asian bullion unit.
- ozt
- Troy ounce = 31.1034768 g
- dwt
- Pennyweight = 1/20 troy ounce ≈ 1.5552 g
- gr
- Grain = 64.79891 mg
- oz
- Avoirdupois ounce = 28.3495 g
Worked examples
1 troy ounce gold coin
One troy ounce is 31.1035 g by definition — 20 pennyweights or 480 grains. On a kitchen scale it would read about 1.097 ordinary ounces.
100 g silver bar in troy ounces
100 ÷ 31.1034768 = 3.215 troy ounces. That figure is what you multiply by the per-ounce spot price.
1 kilogram gold bar
1,000 g ÷ 31.1034768 = 32.15 troy ounces, which is why kilo bars are priced at about 32.15 × the ounce price.
10 troy ounces
10 × 31.1034768 = 311.03 g. In avoirdupois ounces that is 10.97 oz, showing how troy and food ounces differ.
Frequently asked questions
How many grams are in a troy ounce?+
One troy ounce is exactly 31.1034768 grams, usually rounded to 31.1 g. A regular (avoirdupois) ounce is 28.35 g.
How many troy ounces are in a kilogram?+
A kilogram contains 32.1507 troy ounces. So a 1 kg gold bar is worth about 32.15 times the gold price per ounce.
Why are gold and silver measured in troy ounces?+
The troy system was used by medieval European merchants and mints, and the bullion market kept it. Prices on the London and New York markets are still quoted in US dollars per troy ounce.
Is a troy ounce heavier than a regular ounce?+
Yes. A troy ounce (31.10 g) is about 9.7% heavier than an avoirdupois ounce (28.35 g). But a troy pound (12 ozt, 373 g) is lighter than a normal pound (16 oz, 454 g).
What is a pennyweight?+
A pennyweight (dwt) is 1/20 of a troy ounce, about 1.555 grams. Jewellers in the US often weigh scrap gold in pennyweights.