The height of columns are calculated in terms of a ratio between the diameter of the shaft at its base and the height of the column. A Doric column can be described as seven diameters high, an Ionic column as eight diameters high, and a Corinthian column nine diameters high, although the actual ratios used vary considerably in both ancient and revived examples, but keeping to the trend of increasing slimness between the orders. Sometimes this is phrased as lower diameters high, to establish which part of the shaft has been measured.