In Defense of Pie Charts, and Why You Shouldn’t Use Them

In the data visualization community, I’m probably best known for experimental projects…for data art, for particle systems inspired by Chemistry and Physics, for audio analysis and mapping, for sharing what I’ve learned while migrating D3 projects to D3.V4.

So why am I writing about pie charts? Because it’s always a good idea to revisit the basics, every so often…and to question our assumptions about those basics.

Developing a data visualization is more than just data structures and algorithms. It’s more than code libraries and tools. It’s important to make time and step away from the code…to understand and follow best practices in data visualization.

For as long as I can remember, I’ve repeated and followed the standard mantra of data visualization: “don’t ever use pie charts”. Why? Well, most of the time they’re just not readable. It’s about how we perceive area, and angles, and more.

But are all pie charts unreadable? Aren’t there any good times to use one? Well, during dinner conversation at a data visualization conference (Tapestry), my assumptions about pie charts were pleasantly challenged. I was genuinely surprised to hear that there actually a few use cases that pie charts are really great for.

I’ll just show a couple that I found interesting.