Encyclopedia · Metals markets
Troy ounce
A troy ounce is the weight unit used for precious metals. It is heavier than the ordinary kitchen ounce — about 31.10 grams against 28.35 — so the two are not interchangeable.
Working knowledge
Every metal quote, contract and invoice you will see is per fine troy ounce. 'Fine' means the pure metal content, not the gross weight of the item.
A one-ounce gold coin at 22 karat weighs more than one troy ounce gross, because it contains one troy ounce of pure gold plus alloy.
Advanced
Fine weight equals gross weight multiplied by fineness. A 1,000-gram bar at .9999 contains 999.9 grams of pure metal, or about 32.15 fine troy ounces.
Confusing gross and fine weight is one of the most common ways a buyer overpays without noticing.
Professional practice
Invoices for larger transactions should state gross weight, assay fineness and fine weight separately, with the price applied to fine weight.
Where people go wrong
- Using avoirdupois ounces in a calculation.
- Paying on gross weight for an alloyed product.
Sources for this entry
- CME Group — COMEX gold and silver futures contract specificationsDeliverable fineness, bar sizes and contract terms that define what the quoted futures price actually refers to.
- Library of Congress — United States Statutes at Large, Volume 1 (1789–1799)The enacted text of early federal law, including the Coinage Act of April 2, 1792, which defined the dollar as a stated weight of silver and set gold and silver coin standards.
Last reviewed 2026-09-14
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