Readability and legibility, -not to be confused with Readability

The following text has been extracted from Wikipedia and concerns the topic of typography. It is a quick introduction on the subject and concers a small area of the wast subject.

Legibility is primarily the concern of the typeface designer, to ensure that each individual character or glyph is unambiguous and distinguishable from all other characters in the font. Legibility is also in part the concern of the typographer to select a typeface with appropriate clarity of design for the intended use at the intended size. An example of a well-known design, Brush Script, contains a number of illegible letters since many of the characters can be easily misread especially if seen out of textual context.


Readability is primarily the concern of the typographer or information designer. It is the intended result of the complete process of presentation of textual material in order to communicate meaning as unambiguously as possible. A reader should be assisted in navigating around the information with ease, by optimal inter-letter, inter-word and particularly inter-line spacing, coupled with appropriate line length and position on the page, careful editorial “chunking” and choice of the text architecture of titles, folios, and reference links.

So what what is the difference?

One of the clearest distinctions between the two concepts was presented by Walter Tracy in his Letters of Credit. These … ‘two aspects of a type’ … are … ‘fundamental to its effectiveness. Because the common meaning of “legible” is “readable” there are those - even some professionally involved in typography - who think that the term “legibility” is all that is needed in any discussion on the effectiveness of types. But legibility and readability are separate, though connected aspects of type. Properly understood … the two terms can help to describe the character and function of type more precisely than legibility alone. … In typography we need to draw the definition … of legibility …to mean the quality of being decipherable and recognisable – so that we can say, for example, that the lowercase h in a particular old style italic is not legible in small sizes because its in-turned leg makes it look like the letter b; or a figure 3 in a classified advertisement is too similar to the 8. … In display sizes legibility ceases to be a serious matter; a character which causes uncertainty at 8 point size will be plain enough at 24 point.’ Note that the above applies to people with 20/20 vision at appropriate reading distance and under optimal lighting. The analogy of an opticians chart, testing for visual acuity and independent of meaning, is useful to indicate the scope of the concept of legibility.

Excellence in perception and comprehension

Legibility ‘refers to perception’ and readability ‘refers to comprehension’.

Typographers aim to achieve excellence in both. “The typeface chosen should be legible. That is, it should be read without effort. Sometimes legibility is simply a matter of type size. More often however, it is a matter of typeface design. In general typefaces that are true to the basic letterforms are more legible than typefaces that have been condensed, expanded, embellished, or abstracted. “However, even a legible typeface can become unreadable through poor setting and placement, just as a less legible typeface can be made more readable through good design.”

Studies of both legibility and readability have examined a wide range of factors including type size and type design. For example, comparing serif vs. sans-serif type, italic type vs. roman type, line length, line spacing, color contrast, the design of right-hand edge (for example, justification, straight right hand edge) vs. ranged left, and whether text is hyphenated.

More aspects of typography >

Other topics such as justified vs unjustified type, use of hyphens, and proper fonts for people with reading difficulties such as Dyslexia, have continued to be subjects of debate. Websites such as ban comic sans, UK National Literacy Trust, and Mark Simsonson Studio have raised debating opinions on the above subjects and many more each presenting a thorough and well-organized position. Legibility is usually measured through speed of reading, with comprehension scores used to check for effectiveness (that is, not a rushed or careless read). For example, Miles Tinker, who published numerous studies from the 1930s to the 1960s, used a speed of reading test that required participants to spot incongruous words as an effectiveness filter.

Saccadic rythms matters

The Readability of Print Unit at the Royal College of Art under Professor Herbert Spencer with Brian Coe and Linda Reynolds[19] did important work in this area and was one of the centres which revealed the importance of the saccadic rhythm of eye movement for readability - in particular the ability to take in (i.e. recognise the meaning of groups of) around three words at once and the physiognomy of the eye which meant that the eye tired, if the line required more than 3 or 4 of these saccadic jumps. More than this is found to introduce strain and errors in reading (e.g. Doubling). These days, legibility research tends to be limited to critical issues, or the testing of specific design solutions (for example, when new typefaces are developed). Examples of critical issues include typefaces (also called fonts) for people with visual impairment,
and typefaces for highway signs, or for other conditions where legibility may make a key difference.

Some commonly agreed findings of legibility research include:

Text typeset using LaTeX digital typesetting software

Readability can also be compromised by letter-spacing, word spacing, or leading that is too tight or too loose. It can be improved when generous vertical space separates lines of text, making it easier for the eye to distinguish one line from the next, or previous line. Poorly designed fonts and those that are too tightly or loosely fitted can also result in poor legibility.

Typography is an element of all printed material. Periodical publications, especially newspapers and magazines, use typographical elements to achieve an attractive, distinctive appearance, to aid readers in navigating the publication, and in some cases for dramatic effect. By formulating a style guide, a periodical standardizes on a relatively small collection of typefaces, each used for specific elements within the publication, and makes consistent use of type sizes, italic, boldface, large and small capital letters, colors, and other typographic features. Some publications, such as The Guardian and The Economist, go so far as to commission a type designer to create bespoke (custom tailored) typefaces for their exclusive use.

Display typography is a potent element in graphic design, where there is less concern for readability and more potential for using type in an artistic manner. Type is combined with negative space, graphic elements and pictures, forming relationships and dialog between words and images. Color and size of type elements are much more prevalent than in text typography. Most display typography exploits type at larger sizes, where the details of letter design are magnified. Color is used for its emotional effect in conveying the tone and nature of subject matter.

Display typography encompasses:

    * Posters; book covers;
    * Typographic logos and wordmarks; billboards;
    * Packaging and labeling; on-product typography; calligraphy;
    * Graffiti; inscriptional and architectural lettering;
    * Poster design and other large scale lettering signage;
    * Business communications and promotional collateral; advertising;
    * Wordmarks and typographic logos (logotypes),
    * and kinetic typography in motion pictures and television; vending machine displays; online and computer screen displays.