The cap height is measured up from the straight line connecting the arm’s eye on the sleeve pattern. There isn't a perfect cap height in pattern making. Every style is different for this point of measure. It’s based on the function or layer of the garment. For example, a ski/snowboard/climbing jacket may have a super short cap height, as shown here. This information and more can be found in The Fitting Book. Visit GinaReneeDesigns.com to get yours.