17 Rules for Successful Diagrams

What is a diagram?

Diagrams are used to illustrate the interrelationships between objects, ideas or concepts. A good diagram tells a story with every line. It is a precisely choreographed piece of graphic design. It explains something which cannot be explained by a paragraph of text.

Here are my top tips for making your diagrams as clear and communicative as possible:

Tips for drawing successful diagrams

1. Before you start, write down in one sentence what you want the diagram to achieve. A good diagram only ever tries to represent one clear idea.
2. Use as few lines as possible. Think very carefully about the weight, style and colour of every line you use.
3. Establish a hierarchy of line types. A good diagram should only ever need 3 types of line.
4. Use dotted or dashed lines only to represent intangible links between things, things which you want to seem hidden, or when you want to suggest something unknown.
5. Use as few colours as possible. Remember that colours are not decoration, they represent different ideas or relationships within your diagram. If there is no need for colour, don’t add any.
6. Certain colours have strong associations which may vary from culture to culture. Grey usually suggests neutrality.
7. Some people cannot see differences in hue (red/green colour-blindness is the most common) but everyone can see differences in tone.
8. Establish a hierarchy for the elements within your diagram. What do you want the viewer to see first? If their eye isn't drawn to one particular element at first glance, they will assume a uniformity of hierarchy in the elements; if their eye is drawn to one element, the viewer will assume that that element is the most important.
9. Position things carefully. Every element within the diagram — lines, text, objects etc. — shows its relation to every other element by the way it is positioned relative to those elements.
10. Use text sparingly, if at all. The point of the diagram is that the thing you’re drawing couldn't be explained in a paragraph of text, so every time you feel inclined to add some text, try to think of a graphical way of showing it instead. If you must use text, treat it like a graphic element.
11. Use arrows. Arrows indicate the flow of the story to the viewer. Remember that arrows can have heads at both ends.
12. The background is part of the diagram. A viewer will tend to disregard a white background, but if you use a colour it becomes part of the diagram itself and must have a meaning.
13. Diagrams can reinforce branding. If your diagram needs colour, use a colour which the viewer already associates with your company.
14. Think about scale. Larger elements seem more important than smaller ones. Elements of the same type should always be the same shape and size unless there is a very good reason for them not to be.
15. Blank space is as important as objects.
16. When drawing a series of diagrams, use the same line types, colours and shapes throughout. The viewer will quickly learn which colours mean what and apply that knowledge to the next diagram in the series.
17. Make your diagram as beautiful as possible.

I’m a little obsessed with the art of drawing a good diagram. If you have any questions you can get in touch with me via Twitter.