Pie Charts
GUIDEWhat a pie chart shows, when to use one, how to read it, and the traps to avoid.
A pie chart is one of the most recognisable charts there is: a circle sliced into wedges, where each wedge represents a category's share of the whole. It answers a single, specific question — how is one total divided among its parts? — and when used for exactly that, it communicates instantly.
How a pie chart works
The full circle — 360 degrees — represents 100% of the total. Each category gets a slice whose angle is that category's share of the total. A category worth 25% of the whole takes a quarter of the circle (90°); a category worth 50% takes a semicircle. Because the slices are cut from the same circle, the reader can see at a glance which categories are large and which are small, and that everything sums to one complete whole.
That last point is what separates a pie chart from a bar chart. A bar chart compares independent quantities; a pie chart specifically shows composition — parts of a single thing. If your categories are not parts of one whole, a pie chart is the wrong tool.
When to use a pie chart
- One whole, a few parts. Budget split across 3–5 categories, market share among the top players, survey responses to a single question.
- The message is "this part dominates." Pies excel at showing that one slice is clearly the biggest, or that the split is roughly even.
- Precision is not the goal. If readers only need the gist — "most of the budget goes to salaries" — a pie communicates that faster than a table.
If you can phrase your takeaway as "X is [a fraction] of the total," a pie chart fits. If your takeaway is "X is bigger than Y by [an exact amount]," reach for a bar chart instead.
When not to use a pie chart
Pie charts get criticised, and usually it is because they were used for a job they are bad at:
- Many categories. Past about six slices, the small ones become slivers that are impossible to label or compare. Group small categories into an "Other" slice, or switch to a bar chart.
- Precise comparison. People judge the lengths of bars far more accurately than the angles of slices. Two slices of 24% and 27% look identical in a pie but are clearly different as bars.
- Change over time. A pie is a single snapshot. To show how a composition shifts across periods, use a line chart or a stacked bar chart.
- Values that are not parts of a whole. Comparing the populations of five unrelated cities is not a composition — those are independent quantities, so use bars.
How to read a pie chart
Start with the largest slice and work down — pies are easiest to read when slices are ordered by size, usually clockwise from the top. Compare each slice to familiar reference angles: a half circle is 50%, a quarter is 25%, and an eighth is around 12%. Use the labels or legend for exact figures, because your eye will only estimate the angles. If two slices look close in size, trust the numbers rather than the picture.
Pie vs. donut charts
A donut chart is simply a pie chart with a hole in the centre. The proportions are read exactly the same way — the hole changes nothing about the data. Its one practical advantage is the empty middle, which can hold a total or a label. Choose whichever looks cleaner for your context; neither is more "correct."
Common mistakes to avoid
3-D pies tilt the circle, distorting the angles readers rely on — avoid them. Exploded slices pulled away from the centre make sizes even harder to compare. Slices that don't sum to 100% mean your categories aren't a true whole. And rainbow colour schemes with no order make the chart harder, not easier, to read.
Make a pie chart
Ready to build one? The pie chart maker lets you enter labels and values (or paste a CSV), switch between pie and donut, recolour slices, and export a PNG or SVG — free, no signup, no watermark.