Figure 1: A floating, tilted, 3D pie chart with shadow trying (poorly)to show usage statistics within a graphics application.

Of course, pie charts in and of themselves are not evil. This blog is really about designers making poor decisions for all the wrong reasons. In order for a pie chart to appear on a web page, somebody chose it over the other alternatives, and probably thought they were doing the right thing. They weren't. Using a pie chart is almost always a bad design decision.

Figure 2: Pie Chart from an Oracle Reports User Guide

A pie chart does not do the job of effectively displaying information in an elegant visual form.  Being circular, they use up too much space while not allowing their labels to line up. Bar charts, line charts, and tables do a much better job. Expert designers, statisticians, and business analysts have documented their many failings, and strongly urge software and report designers not to use them. It's obvious to them that the pie chart has too many inherent defects to ever be used effectively.

Figure 3: Demonstration of how comparing data between multiple pie charts is difficult.

Yet pie charts are still used frequently in today's software applications, financial reports, and websites, often on the opening page as a symbol of how the data inside is represented. In an attempt to get a flashy colorful graphic to break up boring text, designers will often settle for a pie chart that looks like pac man, a colored spinning wheel, or a 3D floating alien space ship.