Common precious metal weight units
Bullion is priced internationally in troy ounces (31.1035 grams), a relic of medieval Troyes in France. Local markets each have their own historic unit, and savvy buyers move between them constantly:
- Troy ounce (oz t) — 31.1035 g. The global benchmark; all spot prices quote this unit.
- Gram (g) — the SI unit. Common for jewellery and small-bar pricing in Europe and Asia.
- Kilogram (kg) — 1000 g, or 32.1507 troy oz. The standard for large investment-grade bars.
- Tola — 11.6638 g, used across India, Pakistan, Bangladesh and the Middle East. Indian bullion bars are typically sold in 10-tola "biscuit" size (116.638 g).
- Tael (Hong Kong / Singapore) — 37.4290 g. The dominant unit in Chinese gold markets; differs slightly from the Taiwanese tael.
- Tael (Taiwan) — 37.5 g. A rounded variant used in Taiwan and some other Chinese-speaking markets.
- Baht — 15.244 g (for bullion). The standard unit in Thailand's bullion and jewellery market.
- Pennyweight (dwt) — 1.5552 g, or 1/20 of a troy ounce. Still used by US scrap dealers and dental gold buyers.
- Grain — 0.0648 g, or 1/480 of a troy ounce. The smallest unit; mostly historical now.
- Avoirdupois ounce — 28.3495 g. The "regular" ounce used for food and most US weights — not the same as a troy ounce. Don't confuse the two when buying jewellery.
Why troy ounces aren't regular ounces
The avoirdupois ounce most people think of (a slice of bread, a letter on a scale) is about 28.35 grams. The troy ounce is roughly 10% heavier at 31.10 grams. So one troy ounce of gold is about 1.097 "regular" ounces. The two systems coexist because the precious-metals trade kept the medieval troy weight while everyday commerce moved on. This is why a single online listing reading "1 oz gold bar" should always be assumed to mean troy ounces — but check the seller's spec sheet to be sure.
Related tools
- Scrap gold calculator for jewellery valuation
- Coin melt value calculator for popular bullion coins
- Portfolio holdings calculator