Tip of the month from PRC
August 1998

Selection of fonts

Updated 5 August 1998 (Adobe Acrobat considerations)

We accept Mastercard/Eurocard/Maestro/JBC and Visa!
Tip of the month is edited by Peter Ring, PRC (Peter Ring Consultants, Denmark)
- consultants on how to write user friendly manuals
If you have corrections, better texts or suggestions for improvements, please let me know.

Background

Which font to use where is one of the top FAQs from technical writers. I will here make a summary of my experiences, added some wisdom from my teachers within the graphic arts.

Introduction

There is no general eternal truth about which font to choose for a certain purpose. It is a compromise based on a lot of considerations:

Readability:

What fonts are the readers most used to read.
The output media (paper, screen, fax, ...)
The background.
General printing space considerations.
Font size.

The type of message (technical, emotional, ...).
If used on-line: availability on the users computer.
Company/organisation policy.
Graphical design considerations.

Let's take a look at these factors one-by-one.

Which font type?

Basically ....

Variable width fonts are easier to read than fixed width fonts. The reason is, that with variable width the individual characters differ more from each other.
A wide font is easier to read than a narrow font - within reasonable limits!
A serif type font is in principle (high-resolution media, same user preference, same training in reading the font, etc.) Easier to read than a non-serif type font, because the individual characters differ more from each other.
If you absolutely want to make a text almost unreadable, use UPPERCASE LETTERS or C APITALS. The reason is, that upper case letters are more alike than lower case letters. Upper-case-only texts are for very short sentences, only, max. 10 characters or so, e.g. "Warning".

But there are a large number of considerations, which may lead to other choices.

The type of message

My teachers within the graphical arts has taught me the following rule-of-thumb:

For technical/scientific texts, talking to the rational side of the readers, use a non-serif font like Arial or Helvetica. This will be the case with most technical writing.
For texts talking to the readers emotions, use a serif type of font like Times Roman. This is e.g. the case with advertising texts, incl. sales letters.
For general texts (e.g. newspapers) the general rules wins, and unless the output media (resolution, etc.) or background favours non-serif types, use a serif type text.
For forms, tables , etc., Where there is a fixed text length in characters to be observed, or where it is important that the letters are placed over each other in a controlled way, use a fixed width font like Courier. In all other cases, use a variable width font.

Readability

Which fonts are the readers most used to read?

A well-known font is easier to read than less known or unknown font. By reading a text with a certain font, you are trained to read that font quickly. Minor differences like the difference between Arial and Helvetica has no importance at all for the readability. My teachers within the graphical arts has taught me the following rules-of-thumb:

Technically oriented readers like engineers are most used to read technical texts because of general acceptance of the "Type of message " rules above. They are consequently reading a non-serif type text faster than a serif text.
Humanistic oriented readers are most used to read newspapers or emotionally oriented texts. They are consequently reading a serif type text faster than a non-serif text.
Commonly used fonts are faster and easier to read than special fonts. Especially the creative fonts are often difficult to read. Consequently use a font within or close to one of common font type families like Times, Helvetica, Courier or Schoolbook.

The output media:

On high resolution media, serif type fonts are basically faster and easier to read than non-serif fonts . See "Basically " above. But this point is less important than which fonts the readers are most used to read.
On low resolution media like fax or screen, the much smaller resolution (d.p.i.) of a screen makes non-serif fonts much more readable, especially those with a fixed stroke width, like Arial or Helvetica.

The background:

When using a bright text on a dark background, preferably use a bold, fixed stroke width, non-serif type because thin lines disappears on a dark background.
The same rule is valid if using a "watermark" background, or a greytone background printed by means of little black dots (screen). Generally, watermarks disturbs the reading.

Printing space considerations:

we all want to be able to put as much text as possible in as little space as possible without loosing readability. This is especially the case with technical publications, where the users' ability to survey the subject is of greatest importance, but generally there are important economical considerations, too.

Serif type texts takes up more space than an equivalent non-serif font because the serifs demands extra space between the vertical strokes.
Different fonts has different relationships between

the size of a small lowercase letter like an "a",
the over-length, e.g. the height difference between a "k" and an "a",
and the under-length, e.g. the height difference between a "g" and an "a".

Within reasonable limits, the higher the small lowercase letter is compared to the under- and over-length, the smaller font size will still be readable. That's why e.g. a 9 point Times Roman is comparable in readability with an 8 point Helvetica.

Letter width: basically within reasonable limits, wider letters are easier to read but also takes up more space. However, in some cases you can go down a point in size with a wider-letter font and still make it equally readable.
The space between the letters has normally been optimised by the font designer, and the readers are most used to the standard spacing. Compressing (or widening!) this space will consequently in most cases reduce the readability.
The more space between the lines (normally expressed in points, too) the better, until double spacing. Example of how to state it: a Helvetica 8/9 point is a 8 point Helvetica with 1 point (extra) spacing between the lines.

The font size (point). Basically, the larger the font, the better readability until the line length becomes too short (less than 30 to 35 characters). But the font size needed also depends on a number of factors:

The font type selected. See "Dfferent font has ... " above.
The readers (young, old, more or less visually impaired, ...). Younger people can read e.g. an 8 point Helvetica (Ariel, etc.) or 9 point Times without problems. Old people need e.g. an 11 point Helvetica or 12 point Times.
The heading, etc. level. As a rule of thumb, a point size factor of 1.4 is suitable between heading levels. Bold text adds typically .5 to 1 "heading level", depending of how bold the bold font is compared to the normal text font.

If used on-line: availability on the user's computer.

If a computer is asked to display a font, it don't know, one out of two things may happen:

It will protest and ask for the requested font.
It will more or less automatically replace the unknown font with another font to alert the user about the problem but still make the information available. Very often the replacement font is a courier type.

It is consequently a good idea to ensure that the font is available on the user's computer. There are three ways to do that:

Use a font, which everybody has got. In the Windows environment, that is TrueType fonts like Ariel (close to Helvetica), Times New Roman and Courier New, and "system fonts" like MS Serif and MS Sans Serif. The system fonts are available in certain sizes, only, e.g. 8, 10, 12, 14, 18, 24 point.
Embed the font within the document, when saving the document. In many programmes, there is a clickable option for embedding the font when saving a file. This makes sure, that the receiver can at least read the document properly.
Include the font, together with a suitable installation procedure executable file and/or description. If you do so, make sure you don't infringe any copyrights!

When using Adobe Acrobat , special attention should be made to the "Distiller/Job options" menu, "Font embedding" tabsheet. If you check the "Subset fonts below", the font will be embedded with a prefix to the font name, i.e. a name which can not exist on the destination system. And so your embedded font will be used instead of the printers local version. For further details, see the Adobe Acrobat "Help" file, chapter 5, "Font embedding".

Company/organisation policy.

Most larger and many small companies has got a graphical line to be followed. In many cases, this includes which fonts to be used where. These rules must of course be followed.

If the fonts chosen are rare or specially designed for the company, there are special considerations to be taken:

The fonts must be easily available internally, e.g. Downloadable from the internal network.
When working with external printers and free-lancers, make sure they get the font(s) to be used.
Don't use them for on-line versions of your documents, unless you have made sure, the users can access the font type, see "If used on-line ", above.

Graphical design considerations.

Less important for technical communication. Of course the font should fit to the general graphical design, but the other points above are more important, and the graphical design must be adapted to the result of the readability, etc. considerations, and not the other way around.

If you disagree with these ideas - or have other relevant points, experiences, or ideas +/-, please e-mail me !

Ideas for new "Tip of the month" subjects are very welcome, too!

Go to last month's tip .
Go to a list of old tips .
Return to the User friendly manuals' homepage .

Free update service
Click here if you want to receive an e-mail whenever this website is updated with major new information, e.g. with a new "Tip of the month" or a new interesting link. The e-mail will briefly describe the content of the update.

Tip of the month from PRC August 1998