font sizes and styles

There are two different types of font styles in western countries: serif and sans-serif.

The former was created first and is the best choice for printed media. Due to the small hooks (the serifs) at the edges of every letter, words are more coherent and thus it is much easier for the human brain to conceive the meaning of it.

The latter is used on screens and street signs and was created to provide a high readability for short content (few words) like headlines, warnings, information etc.

Since a presentation focuses on few things (meaning one aspect) per slide and is usually shown in large scale using a presenter in front of an audience, you should use a sans-serif font. The size should be big enough so that the people in the last row should be able to read your slide without the usage of a binocular. This means that headlines should be font size 42-48 points and content 28-36 points. Not smaller.

Do not forget that a presentation is not a documentation! If you need a smaller font size than the recommended ones this means that you probably have too much content on your slide. In this case you should think about ...

• ... splitting it into multiple slides,
• ... shorten your sentences without loosing their meaning (e.g. using only the headlines on your slide), or
• ... using an image instead to explain the content since it seems to be too complicated if it can not be explained in less words.

Do not change your font style and font sizes on a single slide. Most of the time I saw this, it was caused by the user copy&pasting content from other sources into her slides. Not only makes this fact it obvious to the audience that your did not care much about your presentation during preparation but also gives the impression that your are not firm in the presented topic.

And don't forget that when you have to present elsewhere where you not use your own computer that non-standard fonts may not be supported by the company's/facility's computer setup. As a result, their default font may change your layout with disastrous consequences! Examples shown on distribution as ppt.