How things are weighed outside the metric system is standardized, which is good. But weights are standardized in two systems! Very confusing. The first system is for precious metals, the second system is for everything else. Here’s what you need to know:
- The avoirdupois system is a measurement system of weights which is generally used for trade goods. The avoirdupois system includes units of weight such as the ounce, pound, wey, stone, and hundredweight.
- The avoirdupois system was initially developed informally, for the wool trade in western Europe, before being officially adopted by the King of England in 1303.
- The English kings used troy weight (named for the French town Troyes) for currency measurements, and in 1527 it became the legal standard for minting coins.
- A pound of feathers weighs more than a pound of gold. Precious metals like gold are weighed using troy weights, in which a pound consists of 12 ounces. Objects such as feathers are weighed using avoirdupois weights, in which a pound consists of 16 ounces.
- The earliest known standard of weight is the beqa, an ancient Egyptian unit which equals from 6.66 to 7.45 ounces. It is still generally used in weighing gems, precious metals, and stones in troy weight.
