Pennyweight is a unit of Troy weight for weighing precious metals. The name comes from the city Troyes, in France, where it has its origins.

Troy Weight
Grain Abbreviation: gn 24 gn to 1 dwt
Pennyweight Abbreviation: dwt 20 dwts to 1 Troy Ounce
Troy Ounce Abbreviation: ozt 12 oz to 1 Troy Pound
Troy Pound Abbreviation: lb. t. 1 lb. t. = 5,760 gn 1 lb. t. = 240 dwt 1 lb. t. = 12 ozt