One of the advantages of teaching the basics of typography to new students is that I get to review and relearn the basics. There is always something new to learn. As students grow as designers the ability to distinguish among the visual clues to identify a typeface becomes second nature. Thus, reviewing terms, parts of the letter, type classification and others is always welcome. Among those visual clues, perhaps the most distinctive is what I like to call the “X” factor. The “X” factor is also called proportions. Simply put, the “X” factor is what determines the typeface’s proportions based on the size of the lowercase x from baseline to the meanline.
But before we go ahead and explain the concept of proportions, let’s define some terms. The baseline is the line where the letters rest horizontally. The meanline is the horizontal line created based on the size or proportions of the letter x of each typeface. This line is relative since it moves up or down according to the size of the letter x. There is also the capline, ascent line, and descent line. These lines are also relative to the typeface’s proportions based on the letter x of each typeface. In other words, the only constant line between different typefaces will be the baseline.
The diagram below illustrates the “X” factor as well as other components.
In the diagram above we can see the baseline as the horizontal line where the letters sit. The descent line is the imaginary line that accommodates the descenders or those parts of the letters p, y, j, q, and g that sit below the baseline. The meanline is an imaginary line created by the lowercase letters that have no ascenders such as a, c, e, g, i, j, m, n, o, p, q, r, s, u, v, w, x, y, z. The ascent line is another imaginary line created by the part of the letters that go up or beyond the height of the capital letters such as b, d, f, h, k, and l. I did not include the lowercase t because its height does not reach the ascent line or the cap line. The lowercase t sits somewhere in between the meanline and the capline. And finally, the capline which is another imaginary line created by the capital letters’ height.
So, what exactly is the “X” factor? The “X” factor is the relative size of the typefaces based on the letter x of that typeface. This is what makes some typefaces look larger or smaller when compared to others of the same size. The diagram below illustrates the “X” factor.
In the above diagram I am demonstrating the effect of the “X” factor. The word typeface is shown using Adobe Garamond 81.77 point size. As you can see the Adobe Garamond’s x is smaller than Myriad Pro Regular x and both are the same size. Thus, Myriad looks larger in proportions even though both letters are the same size. Why is this important? The importance of understanding the “X” factor is that the designer is able to choose a typeface for a layout based on how many pages and words are there. If the designer is limited in the amount of pages or space, the understanding of size and proportions being relative to each typeface, will help the designer make efficient decisions when choosing a typeface. These decisions are not only about text length, but also relate to choosing typeface for headlines, subheadlines, captions, and callouts among others. Keeping in mind that some typefaces have a large “X” factor, for example, helps the designer determine how small or large the type can be on a given text. Some typefaces can be as small as 7 points and because having a large “X” factor, legibility is not affected. The diagram below shows the direct relationship between sizes and proportions.
The typefaces above do not look uniform. Though they are all the same size, they all look different and occupy different spatial length altering our perception. (Please keep in mind, the image is reduced for the article, but give it a try at home).Thus, if we have lots of body copy we might opt for a smaller proportioned typeface, or if we want our headers to be large and feel large, we might opt for a large proportioned typeface. The principle to remember is that all typefaces are not made equal, but among their family members there is consistency.
Carter, Rob, Ben Day, and Phillip Meggs. Typographic Design: Form and Communication. 3rd ed. Wiley.
Samara, Timothy. Typographic Workbook. 2nd ed. Rockport.