A pennyweight (dwt) is a unit of mass equal to 24 grains, 1⁄20 of a troy ounce, 1⁄240 of a troy pound, approximately 0.054857 avoirdupois ounce[1] and exactly 1.55517384 grams.[2] It is abbreviated dwt, d standing for denarius – (an ancient Roman coin), and later used as the symbol of an old British penny (see £sd).