Troy ounce conversion reference
The troy ounce is the standard weight for precious metals worldwide. It dates to medieval European trade and is still used today on all commodity exchanges. One troy ounce is exactly 31.1035 grams (NIST standard, NIST SP 811).
Complete conversion table (1 troy oz)
| Unit | Equivalent | Notes |
|---|---|---|
| 1 troy oz | 31.1035 g | NIST exact value |
| 1 troy oz | 20 dwt | dwt = pennyweight |
| 1 troy oz | 1.09714 avoirdupois oz | ~10% heavier than kitchen oz |
| 1 troy oz | 0.031103 kg | Or 31.1035 g ÷ 1000 |
| 1 troy oz | 0.068571 lb | Avoirdupois pounds |
| 1 gram | 0.032151 troy oz | Divide grams by 31.1035 |
| 1 dwt | 0.050000 troy oz | Or 1.5552 grams |
| 1 kg | 32.1507 troy oz | 1000 ÷ 31.1035 |
Why two types of ounces matter
The avoirdupois ounce (used for food, postal, body weight) equals 28.3495 grams. The troy ounce equals 31.1035 grams. Gold at $4,134/ozt: if you accidentally weigh in avoirdupois oz and treat it as troy oz, you overstate your gold by 9.7%. For a 10 oz bar that error is over $400. Always confirm which ounce a scale or buyer is using.