AGC analysis
The troy ounce: gold's unit of measure
A troy ounce weighs about 31.1 grams, roughly 10% more than an everyday ounce.
American Gold Council · Editorial
Published November 8, 2026 · Updated November 11, 2026
Precious metals are weighed in troy ounces. One troy ounce equals 31.1035 grams, while the avoirdupois ounce used for groceries is 28.35 grams.
That difference matters when comparing a jewelry scale reading with a bullion quote. Twelve troy ounces make a troy pound, but the industry almost always speaks in ounces, grams and kilograms.
A standard large bar traded between banks weighs around 400 troy ounces. Common retail bars range from one gram to one kilogram.
Whenever you calculate the value of gold you own, confirm the unit first; our calculators use troy ounces and grams.
Source: NIST Handbook 44: Weights and measures
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