One of the earliest definitions of the inch was based on barleycorns, where an inch was equal to the length of three grains of dry, round barley placed end-to-end.
Common food items that can be used to show tumor size in cm include: a pea 1 cm , a peanut 2 cm , a grape 3 cm , a walnut 4 cm , a lime 5 cm or 2 inches , an egg 6 cm , a peach 7 cm , and a grapefruit 10 cm or 4 inches.