Observations on Access

Legibility is a fundamental aspect of both graphic design and typography. Unlike readability, though which is focussed on the characteristic of the overall text, legibility refers only to the clarity of single characters of type. While the two are distinct, they are related and should be considered together – specifically when selecting a typeface for a particular role or function.

Legibility describes a font | Readability its function.

The Weight of a typeface is an important factor in its selection for use – be that thin, regular or bold, they all have a role to play. The most readable are a typeface of medium weight. A typeface that is too light in weight can become difficult to distinguished from its background. A typeface that is too bold can lose the counter-form (the negative space that is fully or partially enclosed by the shape of each letter) that is essential to good legibility.

Legibility is reduced in fonts that are designed with either extremely thick or extremely thin strokes. This is because thin strokes are less visible and counter-forms are decreased by the thick strokes. Fonts with greatly contrasting strokes will also, when used in long passages of text, generate a visual momentum or dazzle effect, making reading uncomfortable and difficult.

Access in document design

Serif / San Serif – there is no clearly definitive answer when discussing legibility in relation to a typeface with a serif or without. Historically serif type has be selected for long passages of text, dominating book production since the birth pf printing. Contemporary studies find little real difference in legibility between serif and san serif typefaces! When selecting typefaces, take into account not only the legibility and how readable they will be in their specific application, but also the reading audience and the document’s final destination. A computer screen is very different from a printed poster – and a digital document can be manipulated (focussing in on separate passages of text) to increase access – if it has been considered at the design stage.

Medium: screen / print | Media: computer / tablet / smart phone – book / newspaper / magazine / poster / flyer etc

Fully accessible document design

Type Size – is one of the most important but controversial elements when discussing legibility. It is an obvious factor that when text that is too small or too large it impacts upon reading – small type reduces visibility and large type forces the reader to view the information in sections rather than as a whole.

It is common to access type set in print across a range of sizes from between 8.5  to 15 point. All of these sizes can be comfortable to read, when set correctly. These are physical, printed pages, held in the hand of the reader and viewed within an arm’s length. Therefore, using the point system as the form of measurement is the correct method of describing them (72 points equal one inch etc). But, some still describe type size in ‘points’ when discussing ‘digital design’ which is incorrect. Digital design is viewed on a computer monitor, tablet or smartphone – all screens are calibrated and measured in pixels not in points.

Apple computer monitors were calibrated at 72 dpi (dots per inch) taking reference from the original point system (72 dots per inch / 72 points per inch). Other brands elected not to follow and manufactured their screens from anything between 72 and 96 dpi. More recently, following developments in LCD / LED display systems Apple has changed its baseline to 96 dpi with many other computer systems following suit and some developing even higher resolution screens. This shift has resulted in no standard calibrated size. With no clear, digital bench mark, it has become very difficult to qualify and discuss legibility of type in terms of its digital size.

X-height – defines the relationship between the body and the ascenders. Typefaces set in the same size may look larger or smaller depending on their respective x-heights. So, typefaces with larger x-heights can be set in smaller sizes, usually without impacting on both legibility and readability.

Column Width or Line Length – Lengthy passages of text are easier to read if they are kept to a short line length – rule of thumb is between nine and thirteen words. This is one of the most important elements to consider when designing any documentation with access in mind.

For greater readability in long, thin columns, select a typeface with a smaller x-height. Optimum word length in short column widths is between four and five words, no less.

Justified / Unjustified Text – type that is set flush left (also known as ragged right) often has more even spacing throughout each line of type. Because the type is aligned on the left, and because each line ending at the right is either longer or shorter than the next, readers can easily locate the beginning of a new line.

Setting Type in accessible documents

Take care not to ‘rag’ the type too much when you set ragged right text. The extreme ragged edge can create an uncomfortable rhythm and draws attention to the shape of the column (not its contents). A ‘soft’ ragged edge should look like a piece of paper loosely torn from top to bottom. Yet, fine typographic detailing should consider a ‘saw tooth’ edge – alternating from short to long lines of text.

Fully justified text (where the column fits neatly between two vertical lines) looks nice, but does have the capacity to generate ‘rivers’ (or ‘rivers of white’ are gaps in typesetting which appear to run through passages of text) when digitally set. This is uncomfortable to read and interferes with the flow of the reader. This can be fine tuned using a combination of inter-letter spacing and horizontal scaling.

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Further Reference

Royal National Institute of Blind People (RNIB) Accessible Information – clear print guidelines.


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Royal National Institute of Blind People (RNIB) Accessible Information – guide for business


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Sensory Trust Making information accessible: Clear and Large Print


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UK Government Accessible Communication Formats

  • Government guidelines – the different contexts for publishing information.
  • A small amount of information in relation to type size, choice and application.
  • Little regarding design and layout,


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© Carl Middleton – March 2023

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If you are working on a project which need full consideration for accessibility and you need design support don’t hesitate to get in contact: carlmiddleton@neatdesign.org

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