Understanding the Troy Ounce: History, Definition, and Uses in Precious Metals

What is a troy ounce?

A troy ounce is a unit of mass used almost exclusively for precious metals and some gemstones. Its precise modern value is:
– 1 troy ounce = 31.1034768 grams

When markets quote prices for gold, silver, platinum, or palladium “per ounce,” they mean per troy ounce.

Brief history

• The name likely comes from Troyes, a medieval trading city in France where merchants used a standard weight system.
• The troy system traces further back to Roman weight units (the uncia), which influenced medieval European measures.
• England adopted troy weights for gold and silver by the 1500s; the United States officially used the troy ounce for precious metals in the 19th century.
• Today the troy ounce is the only commonly used remnant of the historical troy weight system.

How the troy ounce compares to the common (avoirdupois) ounce

• 1 avoirdupois ounce (the standard ounce used for most goods) = 28.349523125 grams.
• The troy ounce is heavier: approximately 9.7% larger than the avoirdupois ounce.
• Grain equivalents:
• 1 troy ounce = 480 grains
• 1 avoirdupois ounce = 437.5 grains
• Pounds:
• 1 troy pound = 12 troy ounces = 373.2417216 grams ≈ 0.822857 avoirdupois pounds
• 1 avoirdupois pound = 16 avoirdupois ounces = 453.59237 grams = 14.5833 troy ounces

Quick conversions

• 1 troy oz = 31.1034768 g
• 1 avoirdupois oz = 28.349523125 g
• To convert grams to troy ounces: troy oz = grams ÷ 31.1034768
• To convert troy ounces to grams: grams = troy oz × 31.1034768

Modern uses and significance

• Precious metals markets use the troy ounce as the standard unit for pricing and trading gold, silver, platinum, and palladium.
• Gemstones are now mostly measured in carats, though troy and grain measures historically appeared in gem trade.
• The troy ounce provides a consistent, internationally recognized basis for valuing and recording bullion and coinage.

Precious metals overview and investment options

• Gold: long viewed as a store of value and a safe-haven asset; prices quoted per troy ounce.
• Platinum: used in jewelry, catalytic converters, and industry; traded as a precious metal.
• Palladium: rarer, used in catalytic converters, electronics, and medical/dental applications; valuable in industrial and bullion markets.

Common ways to gain exposure to these metals:
– Physical bullion (coins, bars) measured in troy ounces.
– Exchange-traded funds (ETFs) that track metal prices — no physical delivery for most investors.
– Mining and metals company stocks — carry company-specific risks.
– Futures and options — used by traders and institutions for price exposure or hedging.
– Certificates and pooled storage products offered by banks and dealers (backing and counterparty risk varies).

Frequently asked questions

• Which is heavier: 1 oz or 1 troy ounce?
  A troy ounce is heavier—about 9.7% heavier than an avoirdupois ounce.
• Are troy ounces still used today?
  Yes — primarily for pricing and trading precious metals.
• What is a troy pound?
  A troy pound equals 12 troy ounces (unlike the 16-ounce avoirdupois pound) and is lighter than an avoirdupois pound.

Summary

The troy ounce is the standard weight unit for precious metals, rooted in medieval and Roman weight systems and still used today to ensure consistency in pricing and trading bullion. Its exact mass (31.1034768 grams) is heavier than the everyday avoirdupois ounce, so accuracy in unit recognition is important when buying, selling, or quoting metal values.