Graphic Design Terms 13-14: x-height and cap height

Example of x-heights in different type stylesIn my previous post, I mentioned x-height. Were you wondering what it meant?

It sounds pretty obvious, right? And it is. So is cap height.
In typography, the x-height is the height of lowercase letters that do not have an ascender or descender, represented by the lower case letter x. It is the distance between the baseline and the mid line of a font. (Picture those middle lines in your cursive writing exercise book or see the first image).
In typography, the cap height is the height of capital letters, i.e. the height between the base of the font and the top of the capital letters, specifically flat capital letters such as H or T, as opposed to rounded letters such as O or Q, or pointed letters such as A or V .
The x-height is generally the midway point between the top and bottom of a capital letter, but is not always the case, depending on the typeface (see the dotted line in image 2).
Example cap heights in differnt type stylesAscenders usually extend to the cap height, however, in some typefaces, particularly script styles, some ascenders may appear above the normal cap height, whereas short ascenders may appear just below the normal cap height in some typefaces.
In typefaces with short ascenders and descenders, the x-height is therefore comparatively bigger than those with longer ascenders and descenders. When comparing two typefaces, the font size may seem bigger where the x-height is large, and smaller where the x-height is small, even though the same type size is used.
In a lot of typefaces, particularly script and decorative styles, the strokes, swirls and embellishments often appear above the x-height of lowercase letters without ascenders (see first image) and above the cap height of capital letters (see second image) as well as lowercase letters with ascenders.