The gold weight units
US gold is priced and traded in a handful of units that are easy to confuse. The table shows each unit in grams and in troy ounces.
| Unit | In grams | In troy ounces |
|---|---|---|
| Gram (g) | 1 | 0.0321507 |
| Pennyweight (dwt) | 1.55517384 | 0.05 |
| Troy ounce (ozt) | 31.1034768 | 1 |
| Grain (gr) | 0.06479891 | 0.0020833 |
| Standard ounce (oz) | 28.34952313 | 0.9114583 |
| Pound (lb) | 453.59237 | 14.5833333 |
| Troy pound (lb t) | 373.24172 | 11.9999999 |
| Kilogram (kg) | 1000 | 32.1507466 |
| Milligram (mg) | 0.001 | 0.0000322 |
| Tola | 11.6638038 | 0.375 |
| Tael (HK) | 37.429 | 1.2033703 |
| Baht (Thai) | 15.244 | 0.490106 |
| Mithqal | 4.25 | 0.1366407 |
| Chi / Mace | 3.75 | 0.1205653 |
The 9.7% trap. A troy ounce is 31.1035 g and a standard ounce is 28.3495 g. Weighing gold in standard ounces and multiplying by the spot price overstates the value by roughly a tenth.
Which unit to use
- Grams are the safest unit for weighing at home.
- Pennyweights (dwt) are what US pawn shops and refiners usually quote. 20 dwt make a troy ounce.
- Troy ounces are how the spot price, coins and bars are priced.
- Tola, baht, tael, mithqal and chi appear on pieces bought abroad or sold by merchants who use them.
Once you have the weight, work out its value with the gold calculator or the pennyweight calculator.
Frequently asked questions
How many grams are in a troy ounce?
One troy ounce is 31.1034768 grams.
How many pennyweights are in a troy ounce?
There are 20 pennyweights (dwt) in a troy ounce, and one pennyweight is 1.55517384 grams.
What is the difference between a troy ounce and an ounce?
A troy ounce is 31.1035 grams. The standard (avoirdupois) ounce on a kitchen scale is 28.3495 grams, about 9.7% lighter. Gold is priced per troy ounce.
How many grams is a tola?
One tola is 11.6638 grams, or 0.375 of a troy ounce.
How many grams is a baht of gold?
One baht of gold is 15.244 grams, the unit used by Thai gold shops.