The classic typefaces from Linotype (now Monotype) known as the Legibility Group are the earliest designs specifically created to be highly legible in a less-than-ideal reading environment. Designed in the 1920s, the goal was to improve the reading experience in newspapers of the day. Decades later, typefaces like ITC Charter and the extended ITC Officina family were designed for maximum legibility when imaged by low- resolution printers. In the mid-1990s, Tahoma and Verdana were created to ensure easy reading on computer screens.

Ever since Apple put fonts into a mobile phone in 2007, designers have been using typefaces in everything from wearables to the Internet of Things. Fonts have found their way into the interiors of automobiles, handheld diagnostic and biometric devices, and even the interfaces of white goods, like refrigerators and washing machines. The problem is that many of the usual typographic candidates don’t perform well in these small—and often legibility-demanding— environments. They were created for print, not screen imaging.

Old faces, new challenges

If you’re strictly a print designer, you might not care. But if you take on just about any kind of digital project, textual legibility can be a very real issue. Dr. Nadine Chahine, type director and legibility expert at Monotype UK, sums up the situation: “We are living in a world where a significant portion of our time is spent looking at computer screens, handheld devices and wearables. Good use of typography provides clear and effective communication, which is desperately needed in a world where we are constantly being bombarded with information.”

Type designers are once again addressing the legibility problem by optimizing classic typefaces specifically for interactive design and creating new designs especially for small screens. These device-optimized fonts go by various names and are available from large foundries as well as boutique font providers. The most prominent are the Font Bureau’s Reading Edge fonts, Hoefler & Co.’s Screen- Smart designs and Monotype’s eText typefaces. On the goal of legibility, David Berlow, president of the Font Bureau, says, “The idea is to make fonts that are as readable as Verdana and remain intact down to nine pixels per em-square without losing the stylistic distinction of the design.” And although the foundries share this common objective, each has attacked the problem in a different way.

Answers from the past

In 2002, the Font Bureau’s long association with the Poynter Institute for Media Studies in St. Petersburg, Florida, enabled it to put these concepts to work in a new suite of newspaper “readability” designs. And now the foundry is doing it again with its Reading Edge fonts, looking to Linotype’s original legibility designs to accomplish its goal. “What the old [designers] did to make type for use at small sizes has been well researched and documented,” Berlow continues. “Designers of metal typefaces increased the space above the baseline and enlarged lowercase x-heights. They made the glyphs proportionally wider. They opened up apertures, added weight slightly and dug ink traps into the acute angles of glyphs.”

Hoefler & Co. also relied heavily on generally accepted legibility design principles, incorporating them into the fonts in real time from the get-go. According to the company’s website, “ScreenSmart fonts aren’t just designed for the browser, they’re designed in the browser. To create them, we first built our own suite of font development tools directly on top of the WebKit layout engine so that our designers could create fonts in the same environment in which people would read them.”

Monotype based its research for its eText fonts on historic documentation as well, but backed it up with extensive clinical study. Its designers began by drawing on Monotype’s vast type and font development resources, housed about 30 miles south of London in its Salfords office, the site of the original Monotype Works. “Optical sizes offered in metal fonts were a great starting place,” recalls Steve Matteson, Monotype’s creative type director. “Small point size master drawings were excellent references for considering proportions and spacing for relatively coarse pixel grids. Newspaper typefaces like Nimrod were also referenced because they were designed for printing on coarse, dull, gray-cast paper in suboptimal printing conditions.” This firsthand information was confirmed through clinical studies with the Massachusetts Institute of Technology (MIT). “We’ve been researching the effect of type and typography on legibility alongside MIT’s AgeLab for many years now,” Chahine explains. “I hope that we continue to do so while we explore this fascinating field.”

Common goals

The conclusions reached by all of the foundries amount to a dead heat on a merry-go-round—they’re pretty much the same. The best text fonts for use on small screens have the following attributes:

• Large lowercase x-heights
• Open counters and large apertures
• Exaggerated features
• Moderate contrast in character stroke thickness
• Recognizable design traits
• Marked contrast between medium and bold weights

The lowercase x-height is an important factor in typographic legibility and readability—especially where screen real estate and available pixels are limited. Type designers have long embraced large x-heights to optimize readability.

Open counters help define a character and have a strong influence on ease of recognition. New legibility designs capitalize on this by incorporating more open apertures where forms close in on themselves. Important design features are exaggerated to make typefaces recognizable at small sizes and low resolution.

Typefaces with strong contrast in character stroke weights generally do not work well on small screens. There are not enough pixels in the limited digital real estate to reproduce the contrast at small sizes. Legibility designs of these styles have increased hairline stroke weights to improve screen fidelity.

To aid in creating hierarchy, legibility designs are markedly different in their various weights and proportions. If weights are too close to each other, they may look the same at small sizes.

Technology steps in

And that’s only about designing the typeface. Once the designs have been optimized, this new breed of legibility fonts is subject to comprehensive digital fine-tuning. Even when typeface designs have been adjusted, the modest resolution of many digital displays still presents a major challenge.

Font hinting, the use of mathematical instructions to adjust an outline font’s display so that it lines up with a rasterized grid, can further maximize character legibility. At lower screen resolutions, 

hinting is critical for producing clear, legible text. The best hinting is done by hand on a character-by-character and point size–by–point size basis—a tedious and time-consuming process.

It still, however, comes down to the typeface design. “TrueType instructions [hinting] are not universally applied,” explains Berlow. “The underlying design of each letterform is essential, especially in rendering environments like Mac OS X that ignore hinting data.”

What’s available?

The majority of the new legibility fonts are based on typefaces already in these foundries’ libraries. The Font Bureau, Hoefler & Co. and Monotype all offer about a dozen families of their most popular text typefaces as optimized legibility designs. The Font Bureau and Monotype provide a modest suite of two weights—plus italics—for most families, and Hoefler & Co. provides six weights plus italics. Fonts from all three foundries enjoy large character sets, supporting most Western European and several Central European languages; Monotype is the only provider of non-Latin scripts. According to Chahine, “Monotype has several non-Latin scripts, including complex scripts like Chinese and Arabic. For example, M Ying Hei is very well suited for on-screen usage. We have even tested it in comparison to several other typefaces of the same style, and it came out on top.”

In addition to modifying existing typefaces for eText, Monotype released the Burlingame, Daytona and Joanna Sans Nova families to address small screens’ text legibility issues.

It’s still about good typography

Even when armed with today’s generation of legibility fonts, designers still must make things work. “I’ve found that interactive designers often forget the enormous population with reading difficulties,” cautions Matteson. “Issues like dyslexia—affecting one in ten—the need for reading glasses and simply the glare of reading outdoors should be considered. When talking to designers, I suggest ample use of white space to reduce visual crowding of icons, text and buttons; a limited number of type styles to establish user interface hierarchy; a modest point size versus a fashionably small one; and typefaces with open forms—humanist styles like Frutiger, Verdana and Open Sans.”

Web designers have lived with text legibility issues since the small palette of web-safe system fonts were replaced by dynam- ically downloadable fonts. But now, interactive design has moved far beyond the World Wide Web. More and more designers are developing textual communication interfaces and displays for small-screen devices. The new crop of legibility designs can enable graphic communicators to create text copy as typographically rewarding on screen as it is in print. ca