Imperial and US customary measurement systems in 1824, to take effect in 1826) and United States customary units which evolved from English Units from 1776 onwards. The earliest records of English units of measure involve the weight (and therefore the value) of Saxon coins. The penny introduced by Offa was about 20 grains (1.296 g). Edward the Elder increased the weight of the English penny to 26 grains (1.685 g), thereby aligning it with the penny of Charlemagne. By the time of the Norman Conquest (1066), it had decreased to 24 grains (1.555 g). This value was subsequently called the "pennyweight" and formed the basis of
Troy weight 7716 BI grains, but after the union, rounded to 7680 BI grains. This divides to 16 ounces, each of 16 drops, each of 30 grains. The rounding makes the ounce and grain equal to the English standard. The Dutch troy system is based on a Mark, of 8 Ounces, the ounce of 20 Engels (pennyweight), the Engel of 32 As. The mark was rated as 3798 Grains, English troy, or 246.084 metric grams. The divisions are identical to the tower system. The troy system was used in the apothecaries' system, but with different further subdivisions. King Offa's currency reform replaced