History + Approximate weights of grains used for trading in antiquity Grain SI masscarob seed 200 mgbarley grain 65 mgwheat grain 50 mg At least since antiquity, grains of wheat or barley were used by Mediterranean traders to define units of mass; along with other seeds, especially those of the carob tree. According to a longstanding tradition, one carat (the mass of a carob seed) was equivalent to the weight of four wheat grains or three barleycorns. Since the weights of these seeds are highly variable, especially that of the cereals as a function of moisture, this is a convention more than an absolute law.
history + approximate weights of grains used for trading in antiquity grain si masscarob seed 200 mgbarley grain 65 mgwheat grain 50 mg at least since antiquity grains of wheat or barley were used by mediterranean traders to define units of mass; along with other seeds especially those of the carob tree according to a longstanding tradition one carat (the mass of a carob seed) was equivalent to the weight of four wheat grains or three barleycorns since the weights of these seeds are highly variable especially that of the cereals as a function of moisture this is a convention more than an absolute law