Pennyweight Pennyweight A pennyweight (abbreviated dwt, from denarius weight) is a unit of mass that is equal to 24 grains, of a troy ounce, of a troy pound, approximately 0.054857 avoirdupois ounce and exactly 1.55517384 grams. In the Middle Ages, a British penny's weight was literally, as well as monetarily, of an ounce and of a pound of sterling silver. At that time, the pound in use was the Tower pound, equal to 7,680 Tower grains (also known as wheat grains). The medieval English pennyweight was thus equal to 32 Tower grains. When Troy weights replaced Tower weights in 1527, the
Troy weight "troni" refers to markets. Watson finds the dialect word "troi", meaning a balance in Wright's Dialect Dictionary. Troy weight referred to the tower system; the earliest reference to the modern troy weights is in 1414. Many aspects of the troy weight system were indirectly derived from the Roman monetary system. The Romans used bronze bars of varying weights as currency. An ("heavy bronze") weighed one pound. One twelfth of an was called an , or in English, an "ounce". Before the adoption of the metric system, many systems of troy weights were in use in various parts of Europe, among