What is X height in typography? The complete X height definition

What is X height in typography? This is one of the many questions you may need to ask as you search for the ideal typeface in a branding or creative project. A font X height is an important indicator of how your typography might look in any given environment.

Not to be confused with the point size (which identifies the entire size of your font), the term X height refers to the height of the lowercase “X” in any typeface, regardless of the point size.

While an X height definition might not seem particularly important outside of the creative landscape, it’s a crucial aspect of typography, as it helps to ensure companies and designers can choose a type which matches the personality and image of the brand.

Today, we’re going to be taking a closer look at X height in typography, and why it’s such a valuable consideration for your branding journey.

The definition of X height in typography

Let’s start with the basics: what is X height?

The term X height is one of many concepts in typography intended to help with the positioning and placement of text in a project. X height describes the highest point of a lowercase “X” in any typeface, and demonstrates how short or tall glyphs in a typeface might be.  

Typefaces with a tall X height generally have a better legibility at smaller font sizes, because the central component of the letter is usually broader and easier to read. A larger white space in letters like “d” “b”, and “m” which align with the X height make the characters easier to perceive.

X height in typography is a relative unit for measuring the proportion of lowercase letters, creating consistency within the wider baseline of the font. The X height of a typeface can vary drastically from one design to another.

Crucially, as mentioned above, X height is not the same as point size, which is a measure of the overall height of the type, from the top of the tallest character’s ascender above the baseline, to the bottom of the longest descender.

Font X height: Is larger best?

X height is just one of many heights measured in typography. Designers also look at points like the “cap height”, which refers to the height of a typeface’s flat capital letters, when measured from the baseline.

You might also measure the maximum height of ascenders with an ascender line.

X height is one of the most valuable tools in ensuring the legibility of any font. A large or small X height can either enhance the readability of a character or make it difficult to perceive.

In general, the additional white space in a larger X height will make the font easier to read in any circumstance.

Larger X heights are usually the choice for situations where you want to prioritize clarity, emphasis, and readability. Certain fonts specifically designed to be legible at smaller sizes deliberately use larger X heights, such as Spartan Classified, or the Antique Olive typeface.

Notably, legibility isn’t the only point you may need to consider when choosing the X height of a typeface. Even in the same point size as a typeface with a lower X height, a typeface with a larger X height would consume more real-estate.

This means you wouldn’t be able to get as much text onto a screen or in a specific design if you’re using a larger X height.

A larger X height can also increase the perceived size and space consumption of ascenders and descenders. Although the line height in the two examples above is the same, the letters look as though they’re clustered closer together, which can create a cramped image.

Designers would need to adjust the leading in their text to increase the visual space between the ascenders and descenders, which would further increase the amount of real estate consumed by the text.

When do companies use a smaller X height?

Often, using a smaller X height in a typeface means the whitespace in the font is reduced, which can lower the legibility of the characters, particularly at smaller point sizes.

However, when the larger X height consumes more space in a project, it can also make the text appear cluttered and more difficult to read without extra tracking and kerning.

The problem with larger X heights becomes even more significant in a bolder font, or a font with a heavier weight, which makes each letter look chunkier and closer together. This means you might prefer to switch to a shorter X height if you’re creating large chunks of text.

The amount of whitespace between characters and around the letters on a page is just as important as the level of white space you can see within each character.

When it comes to X height, bigger isn’t always better. While individual letters might be more visible, the text overall can become harder to read.

Companies tend to prefer smaller X heights when they’re creating content for a website, leaflet, or something which requires a lot of text separated into paragraphs.

By using leading and kerning correctly, it’s possible to ensure a font with a small X height can still be just as legible as something with a large X height, even at a smaller point size.

At the same time, a smaller X height also allows designers to take up a lot less real estate, which makes it possible to fit a larger amount of text into any given space.

Provided the ascenders and descenders on your typeface aren’t too long, you can also make the gaps between the various lines of fonts seem greater with a low X height.

How do you choose the right X height?

Like most things in branding and design, X height in typography can be difficult to get your head around at first. The most important thing to remember is there’s no one-size-fits-all when choosing the right typeface.

When it comes to practicing typography, you’ll need to consider everything from X height to kerning and tracking carefully to suit each situation.

A larger X height which makes your font appear clearer and more legible in a header on a blog page might make the same content look cluttered and difficult to read when used in the body text.

Pay attention to the space around and inside the typeface in any environment, to ensure it has plenty of room to breathe.

You may find if you want to continue using the same X height and style of type for all of the content on a page, you need to take extra precautions to ensure the font is legible in every environment. This could mean adding further kerning or leading to various parts of your page.

Don’t forget to pay close attention to how the other heights and sizes in the font affect the overall image too. A long ascender or descender in a typeface will make a larger X height much more difficult to work with if you’re producing large amounts of text.

Making the most of X height

X height in typography is just one of the many concepts you’ll need to consider when creating the perfect design for any type-based project.

When choosing your X height, make sure you consider each element of the typeface carefully, from whether it uses serifs, to whether there are any complex ascenders and descenders you need to be aware of.

If you’re trying to pair typefaces for a design, it’s also worth noting mixing typefaces with similar X heights is usually a good idea to create harmony, while opposing X heights create a sense of dissonance.

Good luck finding your best type! 

Fabrik: A branding agency for our times.