Click here to buy from Amazon. Mobile and small-screen design is largely about communicating information to the user. More often than not, regardless of how exciting and shiny the interface is, this will still be centered on the display of text content.

Mobile typography is about the selection and use of all the type elements within the design. It is only partly about the selection of the correct font and face, and has a great deal to do with selecting display technologies, understanding sizes, and applying conventional design methodologies (size, shape, contrast, color, position, space, etc.) to best employ the type elements.

Challenges of Mobile Typography

Computer-based type, especially for Internet display, has always been a challenge due to display technologies (resolution), availability of type, color and contrast reproduction variations, and size variations. Mobile devices take these issues, magnify them, and add a spate of unique environmental and use-pattern issues. The primary barrier is of technology, and the primary concern is of readability within the user’s context.

Type originally existed as shapes cut out of metal. When digital typesetting first became commercially viable, this model was followed and these letterforms were turned into vector glyphs, mathematically describing the shape of the character.

Smartphones now generally support this sort of type, and may include many fonts and faces and scale uniformly, allowing almost unlimited display options. Custom type can be included with applications loaded to the device relatively easily, and web-based font embedding is now appearing as well.

Older and low-end devices, including the billions of feature phones in the world, mostly only support “bitmap” fonts. These do not use vector glyphs, but instead draw each character as a small graphic of pixels. For each size or weight, a new set of type images must be loaded. Only a small number of fonts will be loaded, and generally only three sizes will be supported by J2ME applications running on these handsets.

All digital display devices render the final shapes as pixels on a square grid. Even ePaper devices must communicate with the stochastic display device with the same technology. Vector shapes, including type, are “rasterized” to comply with this format, and turned into pixels. Subtle angles and curves can become lost, or appear jagged regardless of antialiasing techniques. See Figure C-1.

Figure C-1. Comparing vector and bitmap (or raster) glyphs

Although very high-resolution devices make some of the problems hard to see, almost eliminating them, the basic issues persist, and should be considered during design, and selection of proper type.

Technology continues to improve, and both digital foundries and OS makers are regularly implementing new techniques to improve rendering and readability.


Although some devices are beginning to allow effectively unlimited type selection, support vector glyphs, and have large amounts of storage and running memory, most mobile devices are still resource- and technology-constrained. General issues of storage on the device, running memory, download times, and cost of network access limit availability of type for mobile application design. As many devices require raster (bitmap) faces, each size is loaded as a complete, different typeface. Most products end up with the device’s default type, or with a very limited set of choices for their application.

Although this challenge will slowly dissolve, it will always be present to some degree. Inexpensive devices, specialist devices (youth, elderly, and ruggedized), and emerging market needs seem to indicate these issues will persist for another several decades at least.


Mobiles are used differently from desktops, and even most print use of type. They are closest, perhaps, to signage in that they must be comprehended by all user populations, under the broadest possible range of environmental conditions (e.g., poor lighting) and at a glance. The typical mobile user is working with the device in a highly interruptible manner, glancing at the screen for much of the interaction. The type elements must be immediately findable, readable, and comprehendible.

This is different from the technical challenge in that it is inherent in the mobile device. Users will always interact with their devices in this manner, so it must always be addressed, regardless of the technical implementation.

An Introduction to Typography

To understand mobile typography, you will need to learn a little of the language and principles of typography in general. Do note that this is a very cursory review of this field. Please use the terms to search for more information, and check the sources listed in the references.

Baselines and measurements

The basic building block is lines and measures (see Figure C-2).

Figure C-2. Baselines, x-height, and some of the other basic ways of measuring type height and vertical position.

The baseline is where all type rides. Note that some round characters can dip below this, but only very little for optical purposes so it is perceived as straight. At most mobile screen sizes, this may not even happen. X-height is the height of the lowercase x, or any lowercase character, excluding the ascenders for those characters. Cap height is the height (more or less) of the tallest ascenders, and of the uppercase characters.

Letter Height and Measurements

During the letterpress era, letters were created from cast "sorts," or blocks of lead, with the letter being a raised portion in the middle. These sorts were arranged together to form words and sentences. Each metal sort was designed to have a specific measurement. The letter’s height was measured from the top to the bottom of the sort, not the actual letter, which could vary. This standard measurement became known as the type’s point size.

Today, type is still commonly referred to by its size in points. Other related measures are also useful to know, and are increasingly supported by modern mobile device OSs. These are the most important measures:







Abbreviations for points and picas can be odd. When alone, “p” is for pica and “pt” is for point, but typographers have a convention (supported by all serious digital design tools still) of “picas” p “points,” as in “3p6,” for example. This may even be encountered as a way to express points without the preceding zero, such as “p6.” Type is always specified as points, such as “72pt.”

Letterforms and their parts

When choosing the appropriate mobile type we must understand that each typeface has unique characteristics that affect its legibility across device screen technologies, reading distances, and screen sizes.

In order to create effective message displays that are legible for mobile displays, understanding the basic elements of type is important. The information that follows will assist you when choosing the appropriate typeface for your design:






Cap height

Descender line






Type is composed of letterforms, and very importantly to the readability, the counter forms made up of the white space inside letters (see Figure C-3).

Figure C-3. Letterforms and counters, or the negative space inside the letterforms.

The space between letters is another sort of counter form, and we will discuss it shortly.

Every piece of the letterform also has a name. There are many more of these, but the following list discusses the most important ones for understanding and selecting type appropriate for mobile and small-screen use (see Figure C-4 and Figure C-5).

Figure C-4. Some of the parts of a glyph (or letterform): the stem, descender, bowl, and crossbar.

Figure C-5. More parts of the glyph: the ascender and serif.

Figure C-6. Stressed versus nonstressed stems. Dashed lines are straight, so you can more clearly see the curve on the stressed type.



Square Serifs

These three basic styles are shown in Figure C-7.

Figure C-7. Types of serifs: sans serif without any serif of the conventional type, and a square or slab serif without notable tapers.

For mobile type, sans serif is often the default choice as it works well enough for all uses, at all sizes. Serif faces are more readable for large blocks of type than sans serif faces. If your application is filled with news articles or something similar, consider if a serif face might work. Square serifs work well, to ensure that the serifs display at the rendered sizes and under difficult lighting conditions. Square (or slab) serif faces are the default faces used in popular eReaders.

All these letterform details matter not just for style, but for legibility and readability. Note that most of the letterform is similar to every other letterform. The bottom half is just a series of undifferentiated legs, as shown in Figure C-8.

Figure C-8. The bottom half of each letterform is just a series of undifferentiated legs. The top is where all the readability happens.

So, fairly small portions; mostly in the top half; their ascenders, descenders, counters, and inter-forms are the keys to readers understanding the form and reading the phrase.

Families and Styles

A font family is a group of stylistically related fonts.

A font is a small group of (generally) very similar typefaces, which mostly will vary in weight. A common weight is “bold.” If you have ever heard the term boldface, that’s because it’s a “bold typeface.”

Black is a weight heavier than bold. Roman, Book, or Normal is the default weight. Thin or light is thinner or lighter, essentially the opposite of bold. Numerous other terms are also used, and some fonts have more than a dozen weights.

Weight will, usually, strongly influence the width of the overall type. Readability in long strings can be quite negatively impacted by large blocks of bold text. Very often, other methods (color, shape, position, whitespace) are more suitable for emphasis than bold on small screens. See Figure C-9.

Figure C-9. Weight will usually change the width and readability of type. Be careful when using weight changes as a part of a focus change or other transient state.

A few fonts are specifically designed to have little or no change in width as weight varies. Some are good for screen display purposes, and can be used to solve these problems if available.

Italics are almost script-like faces which complement the normal faces. They are generally both tilted and with additional curves and more decorative serifs. Oblique is the same font more or less just slanted over as a sort of fake italic.

Italics and obliques are not suggested for any purposes on displays with less than about 150 pixels per inch. The angled forms, much like stressed verticals, cannot be rendered sharply. The stairstep effect is noticeable even with type-specific antialiasing techniques. Over about 200 ppi, this begins to become less noticeable, and such types can be used effectively.

Using large blocks of all caps, bold, or italics (or obliques) will result in reduced reading speeds, and lower comprehension. The best results are achieved with mixed case (both uppercase and lowercase) Romans. This can apply even to small passages, such as titles, so if readability is critical consider testing the use of styles such as all-caps titles to be sure they work.

All-caps is sometimes used for emphasis, but this is not always useful, and may provide effectively less emphasis due to reduced legibility.

Space: Kerning and Leading

Proper spacing between characters and lines of type is crucial to readability, but must often be handled automatically for interactive systems. Even well-designed ones must take into account multiple screen sizes and aspect ratios, and sometimes even user-controlled zoom. There is little room for the designer to individually kern letter pairs.

Instead, be aware of the issue, pick fonts that are well designed, and use type display tools that respect the embedded kerning tables and work well for the devices and functions you are designing.

The key spacing attributes are:



Figure C-10. Kerning, showing space between, or space overlapping, individual letterforms.


Figure C-11. Leading is the vertical distance between lines.

Many typefaces suitable for mobile display have very small descenders to help you eliminate extra leading, and fit more information on a page.

Most languages have some accent characters. These are usually placed above the letterform, occupying the ascender space for lowercase characters, but an above-cap-height space for uppercase characters. Typically, this will require very large leading to enable readability of the accents. See Figure C-12.

Figure C-12. Accents above the cap height, and a trick to avoid this.

This generally is unacceptable for small-screen display, and some faces have special letterforms that fit the accent and character within the cap height. If your application must support accent-enabled languages, consider the effect this will have on your design.


Alignment of type is used as a design tool, and to make the text fit appropriately. All type is “aligned.” Some is justified, but this is a subset. Available types of alignment are:

Left align

Right align


Justify left

Justify right

For narrow columns, texts with long words (such as technical jargon), or systems with poor tracking control (such as those that only adjust interword spacing) distracting “rivers” of whitespace may appear in the text. If this is common, justification may not be suitable.

Do not use monospace fonts and additional spaces to simulate justified paragraphs. This is highly unreadable.

Guidelines for Selecting a Typeface for Mobile and Small-Screen Devices

Research shows that reading from a computer screen is about 25% slower than from pa- per. Many mobile devices, due to size or environmental complexities, can make this even more challenging. Understand the principles of type and the limits of mobile to help you make appropriate decisions for your content, and your users. See Figure C-13.

Must have:

Figure C-13. Some pointers to selecting suitable mobile type.

Should also:

Non-Latin languages will have additional requirements. As always, be aware of regional needs and cultural distinctions.


General Type Background

This is a significant subject, and there are many books, and other resources. I'll add my favorites over time. Books are the best, so check the references, but they are book length, so try these first.

Foundries and Catalogs

While no longer usually casting metal type, places that produce type as distributable products are still called foundries.

Display technologies

Type blogs and books

Mobile type info

Some is from foundries, so is self-serving, but we only post those that are largely or completely true

Next: Italics and Obliques For Digital Display

Discuss & Add

Please do not change content above this line, as it's a perfect match with the printed book. Everything else you want to add goes down here.

All Caps?

I just read the other day a study that seemed to say readability of all-caps went up for those accustomed to it. I lost the link, but it's interesting. Someone find it.


Yes, we sometimes have minor contradictions in the book. Here, we go with the classic take that well-formed serifs (printed at decent resolution) help readability. This may not be universally true, but we can discuss further.

A Bunch More Reading for You

A lot of the topics in this section started being written down in this blog post, and not all the links made it across to the book, or even to the resources pages. So, here they are quite unordered for now.

Make a new section

Just like this. If, for example, you want to argue about the differences between, say, Tidwell's Vertical Stack, and our general concept of the List, then add a section to discuss. If we're successful, we'll get to make a new edition and will take all these discussions into account.

Introduction to Mobile Typography (last edited 2014-02-08 01:11:15 by shoobe01)