The right chart starts with a question, not a chart type. Before you pick one, finish this sentence: "I want the reader to see…". The answer points to a family of charts. Within that family, the shape of your data picks the winner.
If you'd rather skip the theory, paste your data into the chart finder and it will draw the best options for you.
"…how things compare"
Use a bar chart. Lengths are the easiest thing for eyes to compare, which is why bars beat almost everything for ranking and comparing. Switch to a horizontal bar chart when labels are long or there are more than about ten items, and a lollipop chart when you want the same thing with less ink.
- Several series per group (regions by quarter): grouped bars.
- Before and after: a dumbbell or slope chart.
- Gains and losses: a diverging bar chart, or a waterfall when the changes add up in sequence.
"…how something changed over time"
Use a line chart. The slope does the talking. Compare up to five or six series on a multi-line chart, and highlight the one that matters. A step chart suits values that jump at set moments, like interest rates, and a bar chart race turns a changing ranking into a story for social video.
"…what something is made of"
For two to six parts of one total, a pie or donut works. A waffle chart makes percentages concrete, with each square worth 1%. For more parts, or parts within parts, use a treemap or sunburst.
"…how values are spread out"
A histogram shows the shape of one set of numbers. To compare groups, use a box plot, a violin plot, or, when every point matters, a beeswarm.
"…how two things are related"
A scatter plot shows whether one measure rises with another. Add a third measure as bubble size with a bubble chart. For patterns across two categories, like day and hour, use a heatmap.
"…how things flow or connect"
A Sankey diagram follows quantities from one stage to the next, which makes it perfect for funnels and budgets. A chord diagram shows flows between a handful of groups, and a network graph shows who connects to whom.
"…where it happens"
Shade countries with a choropleth map for rates and percentages. For totals, like population or sales, use a bubble map: shading by totals makes big countries look important just because they're big.
"…one number"
Sometimes the best chart isn't a chart. A big animated number, or a gauge against a target, says it faster.
Three rules that fix most charts
- Start bars at zero. A cut-off axis turns small differences into dramatic ones.
- Highlight one thing. Grey out everything except the bar, line or slice your sentence is about.
- Say the point in the title. "Sales doubled in 2023" beats "Sales by month".