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
Imperial and US customary measurement systems the Troy units of weight—the troy ounce used to this day for weighting precious metals. Edward I (1272–1307) broke the link between a coin's value and its weight when he debased the English coinage by introducing a groat (four pence) which weighed of 89 grains rather than the expected 96 grains. The groat was further devalued in the 1350s when its weight was reduced to 72 grains. During Saxon times land was measured both in terms of its economic value and in terms of its size. The Domesday Book used the hide, an economic unit of measure. In other references