Pie Chart

A pie chart is a circular chart split into wedges, where each wedge's angle (and area) is proportional to its share of the total. It shows composition — how a single total divides into parts at one moment — such as traffic share by channel or budget split by platform. The whole circle represents 100%.

Use a pie chart sparingly: when you have a single total, just 2–5 categories, and one clearly dominant slice or a simple 'this vs the rest' story. It works when the exact values matter less than the rough proportion. For anything more — many categories, similar-sized slices, or comparing parts precisely — a bar chart is easier to read because lengths compare better than angles.

Because people judge angles and areas poorly compared to lengths. When slices are similar in size, it's nearly impossible to tell which is bigger without labels, and comparing across two pies is worse. Many slices become an unreadable rainbow. Pie charts aren't always wrong, but for accurate comparison a sorted horizontal bar chart almost always communicates the same data more clearly.

Keep it to about 2–5. Beyond five, slices get thin, colors multiply, and the proportions blur. Group small categories into a single 'Other' slice, or — better for many categories — switch to a bar chart. If you find yourself adding data labels to every slice just to make it readable, that's a sign a bar chart would serve better.

A donut chart is a pie chart with the center cut out. Functionally they're the same — both show part-to-whole via slice angle — and they share the same limitations. The hole can hold a total or label and some find it cleaner, but it doesn't fix the core readability issues. Choose either for a simple 2–5 category split; choose a bar chart when precise comparison matters.