Avoirdupois, and Troy Weights

Avoirdupois Weight System

• This is the weight system Americans use on a daily basis. Also called "dry" weight, as in "dry" ounces.
• 1 Avoirdupois Ounce (oz) = 437.5 grains*
• 1 Avoirdupois Pound (lb) = 7000 grains
• 1 lb = 16 oz
• 1 oz = 28.35 grams
• 1 oz = .9115 ozt (Troy ounce)

Troy Weight System

• Precious metals such a gold, silver, and platinum are usually (but not always) weighed using the troy weight system.
• 1 Troy ounce (ozt) = 480 grains
• 1 ozt = 31.1 grams
• 1 Troy pound = 5,760 grain
• 1 Troy pound = 12 Troy ounces
• 1 ozt = 1.097 oz (Avoirdupois ounce)

Avoirdupois and Troy Conversions

• 1 troy ounce (ozt) = 1.097 avoirdupois ounce (oz)
• 1 avoirdupois ounce = .9115 troy ounce

*1 grain = 0.0648 grams. Metric grams are consistent throughout, e.g., there is no such thing as a Avoirdupois gram or a Troy gram. A gram is a gram is a gram.

< Back