Please do not use 3D pie charts. They are evil.
Okay, “evil” may be an overstatement. But they are inefficient and potentially misleading, and the combination of those are a data nerd’s equivalent to evil.
This is not an original idea. This argument is really about how pie charts are bad, and adding 3D makes them even worse. For a survey of the pie charts are bad argument, check out this, and this, and this. Let’s not forget the godfather of visualization, Edward Tufte, famously wrote the following in “The Visual Display of Quantitative Information”:
A table is nearly always better than a dumb pie chart; the only worse design than a pie chart is several of them, for then the viewer is asked to compare quantities located in spatial disarray both within and between charts [...] Given their low density and failure to order numbers along a visual dimension, pie charts should never be used.
Part two of the argument is that adding 3D makes them worse. For some background, check out this, and this, and this. The underlying point is that 3D tends to skew how we perceive the data. You may think you are adding depth and visual intrigue, but you are actually making it harder to understand.
Don’t believe me? Here is a simple exercise I used in a recent presentation for WorldatWork.
Here is a beautiful 3D pie chart showing four made up sales people and their relative results in Q1 of a made of year.
Yep, I crushed it.
Now here is another beautiful pie chart for the same team the following quarter.
Ok, Bryan got me this time.
Or did he?
The charts represent the same data:
The only difference between the two charts is that they are rotated 130 degrees relative to one another. I spun one chart (Excel even has a setting for this: “X Rotation”) to change what shows up in front and in back, which tends to skew what the human eye perceives as larger.
As described by the linked arguments about pie charts and 3D, they require your reader to measure an area and to do so with the pie slices occupying disproportionate real estate in the chart thanks to the 3D. That’s not a natural thing to do.
If your goal is to make something look larger, use a 3D pie chart and highlight it in front. If you actually want your audience to understand the data, find an alternative.
A few of my favorite bloggers have offered alternatives to the pie chart (and by definition 3D pie charts as well). Cole Nussbaumer Knaflic and Nathan Yau both like bar charts and stacked bars, Nathan offers the bubble chart, and Cole suggests a slope graph or just saying the number. In my opinion, all are worthy of consideration case by case. I personally default to the bar chart because people know how to read them intuitively. Comparing lengths is something natural and easy, and you can fit a lot of bars in a relatively compact space
My final point: Your audience will be wowed by a simple, intuitive visualization. They won’t be wowed by adding 3D to a chart. Wow them with the truth, not lipstick. Sure, aesthetics matter… but focus on other drivers of clarity to make a chart that makes an impact.