Font point size is not a measure of the height of the font character. Font point size comes from the measure of the thickness of old lead type. The size of the font character is less than the width of the lead type; some font characters could be half the thickness of the metal type or point size. Not all font characters are the exact same size in a given point size. It is always a good idea to give the customer a proof or copy, so the customer can see the type and specify a larger or smaller size if it does not match their expectations.