Gold and silver are priced per troy ounce — a unit about 10% heavier than the ounce your kitchen scale shows. Confusing the two is the most common (and most expensive) beginner mistake in precious metals: weigh your silver in kitchen ounces, multiply by spot, and you will overvalue it by roughly 10% — then feel cheated by a dealer who did the math right.
The two ounces
| Unit | Grams | Used for |
|---|---|---|
| Troy ounce (ozt) | 31.1035 g | Gold, silver, platinum, palladium |
| Avoirdupois ounce (oz) | 28.3495 g | Everything else — food, mail, body weight |
The name comes from Troyes, the medieval French fair town whose weights became the standard for precious metals trade. Both systems share one tiny unit — the grain (64.79891 mg): a troy ounce is 480 grains, an avoirdupois ounce 437.5 grains.
The full troy family
| Unit | Equals | Grams |
|---|---|---|
| Grain (gr) | 1/480 ozt | 0.0648 g |
| Pennyweight (dwt) | 1/20 ozt | 1.5552 g |
| Troy ounce (ozt) | 20 dwt | 31.1035 g |
| Troy pound | 12 ozt | 373.24 g |
Watch for pennyweight in particular: jewelry and scrap buyers often quote per dwt because the number sounds bigger than the per-gram price. $40/dwt is $25.72/g — always convert before comparing offers. Our per-unit pages show live prices in every unit: gold per pennyweight, per gram, silver per grain, per troy ounce.
Practical rules
- Weigh in grams. Grams are unambiguous; both ounces invite mistakes. Divide by 31.1035 when you need troy ounces.
- Check scale mode. Cheap pocket scales toggle between g, oz, ozt and dwt — a scale stuck in oz mode silently understates troy weight.
- “1 oz” on a bullion coin always means troy. A Silver Eagle is 31.1 g, not 28.3 g.
The bullion calculator accepts grams, troy ounces, avoirdupois ounces, pennyweight, grains and kilograms, and converts between all of them at the live spot price — the safest way to avoid unit slip-ups entirely. The same units work in the scrap gold and sterling calculators.
Frequently asked questions
How many grams are in a troy ounce?
31.1035 grams. The everyday avoirdupois ounce is 28.3495 grams, so a troy ounce is about 9.7% heavier.
What is a pennyweight?
1/20 of a troy ounce, or 1.5552 grams, abbreviated dwt. Jewelry buyers often quote scrap gold prices per pennyweight — convert to grams before comparing offers.
Is a troy pound heavier than a regular pound?
No — lighter. A troy pound is 12 troy ounces (373.2 g) while the everyday pound is 16 avoirdupois ounces (453.6 g). The troy ounce is heavier, but the troy pound is lighter.