Weight is quoted in troy ounces, which are heavier than the ordinary ounce at roughly 31.1 grams. One ounce is the standard for licensed silver issues and where most series live.

Larger formats exist for a design reason rather than a bullion one. Two, three and five ounce pieces give an engraver the surface and thickness needed for high relief and elaborate colour work, which is why the most ambitious issues tend to be the heaviest.

Gold issues run in the other direction, often half gram or quarter ounce, keeping a licensed gold piece within reach.