A slide is not a document. The audience looks at it for a few seconds while listening to the speaker, often from a distance, sometimes on a screen shared in a video call. Anything that needs careful reading competes with the speaker's voice, and the slide usually wins: the audience reads and stops listening.
Designing readable slides therefore means reducing what has to be read and making what remains immediate.
One idea per slide
The most useful rule is also the simplest: each slide communicates a single idea. If a slide contains the problem, the solution and the costs, that is three slides.
More slides with little content do not make the presentation longer: the time depends on what you say, not on the number of screens. In exchange they make the thread easier to follow.
Titles that make a claim
A slide title is often a label: «Results», «Costs», «Current situation». You can do better by writing as the title the conclusion the slide demonstrates:
| Label title | Title that makes a claim |
|---|---|
| Response times | Response times halved after the migration |
| Costs | The new system costs less than the current one from the second year |
| Backup | Laptops are not covered by any backup today |
Viewers get the point even without reading the rest, and anyone flipping through the slides after the presentation can follow the reasoning by reading the titles alone.
How much text
- Few lines, short ones. If a slide needs full sentences to be understood, that text probably belongs in the speaker notes or in a handout.
- No paragraphs. A bulleted list of three or four items of a few words each is the reasonable maximum.
- Large text. As a guideline, body text should rarely go below 24 points and titles work well above 32. A practical test: view the slide full screen from three or four metres away, or shrunk the way it would appear in a video call.
- Sans-serif, highly legible fonts, at most two families across the whole presentation.
Contrast and colour
- Strong contrast between text and background: dark text on a light background or the reverse. Mid-tone combinations, such as grey on light blue, vanish on projectors, which reduce contrast.
- No text over photographs without a band of solid colour behind it.
- Colour as a signal, not decoration: a single highlight colour to point out what matters.
- Do not rely on colour alone to distinguish information: people who have trouble telling red from green will not see the difference. Add labels or shapes.
Charts in slides
A chart designed for a report rarely works on a slide. It needs simplifying:
- Show only the data needed for the slide's message. If the point is the comparison between two years, the other eight are not needed.
- Label series directly instead of using a separate legend.
- Remove the superfluous: dense gridlines, borders, three-dimensional effects, shadows.
- Highlight the key element with the accent colour and leave the rest in grey.
- Write the conclusion in the title, as for the other slides.
Pie charts with many slices and three-dimensional charts are almost always best avoided: they make it hard to compare sizes, which is the very purpose of the chart.
Images
A relevant, good-quality, full-bleed image can be worth more than a list. Generic decorative images, on the other hand, take up space without adding anything. Screenshots should be cropped to the useful part and enlarged: a whole interface shrunk onto a slide is unreadable.
The slide master
The slide master (in PowerPoint View › Slide Master, in Impress View › Master Slide) is the equivalent of styles in a text document. It defines fonts, colours, the position of titles and placeholders, logo and numbering for all slides.
Working on the master instead of individual slides has the same advantages as styles:
- changing a font or a colour updates the whole presentation;
- titles and text always stay in the same position and do not «jump» from one slide to the next;
- titles entered in placeholders are recognised as such, which matters for accessibility and for PDF export.
Prepare a few well-made layouts, for example title and text, title and image, section slide, closing slide, and always use those.
Animations and transitions
Use animations only when they serve a purpose: revealing points one at a time as you talk about them, or showing a sequence. Elaborate transitions between slides distract and, in a video call, can appear jerky.
In short
- One slide, one idea: more simple slides beat a few crowded ones.
- Titles stating the conclusion keep the reasoning readable afterwards too.
- Little text, large, with strong contrast; the rest goes in the speaker notes.
- Charts should be simplified, directly labelled and with the key element highlighted.
- The slide master ensures consistency the way styles do in a document.
