Troy Ounces vs. Avoirdupois Ounces

A Guide to Understanding Precious Metal Weights

The standard weight measurements used for all precious metal products are Troy ounces and pounds. All legal tender silver, gold and platinum coins are struck according to these Troy weights, which are not to be confused with the Avoirdupois weights. Avoirdupois measurements are used for coarse dry weights such as grain, flour, sugar, tea, etc., and are the units of weight you likely learned about in school.

The term Avoirdupois was adapted from the French phrase “aveir de pois” or “aver de peis” – which roughly translates to “goods of weight.” Precious metals, gems and drugs use the Troy system. By the way, the Troy system is not named for the Ancient Greek City of Troy, but for Troyes, France – where they were first introduced. Troy weights are also called Apothecary weights, due to their use with medical drugs.

Here are the basic specification comparisons between Troy and Avoirdupois weights: 

Troy Ounces > Avoirdupois Ounces

  • 1 Troy Ounce = 31.1035 grams
  • 1 Avoirdupois Ounce = 28.3495 grams

In other words, a 1 ounce silver coin is heavier than an ounce of tea.

Troy Pounds < Avoirdupois Pounds

  • 1 Troy Pound = 12 Troy Ounces (373.242 grams)
  • 1 Avoirdupois Pound = 16 Avoirdupois Ounces (453.592 grams)

In other words, a 1 Troy pound bag of silver coins is lighter than a pound bag of rice!

It's important to remember that most household scales weigh in Avoirdupois ounces only. If you place a pound of silver coins on your household scale, it will appear to weigh only .823 pounds.

Make this a hands-on learning experience with a 1 Troy oz. Silver Coin from our broad selection!