Pennyweight

Pennyweight (German: penny weight ) is a non- SI-compliant unit of mass . It comes from the Anglo-American system of measurement (Troy or Apothecaries' Weight), the unit symbol is dwt.

1 dwt. = 24 gr. = 1.55517384 grams

1 troy pound = 12 oz. = 240 dwt. = 5760 gr. = 373.2417216 grams

1 pound sterling = 12 shillings = 240 pence

Originally, 240 penny coins were minted from one pound of silver. The one penny coin therefore weighed exactly one penny weight. The abbreviation dwt came from the fact that the abbreviation for penny was a "d".