Use a bar chart instead of a pie chart to compare share sizes
For comparing shares within a single total, use a bar chart instead of a pie chart to improve readability and mitigate hard-to-see small differences for readers.
- purpose:select
- basis:heuristic
- task:compare
- chart:bar:use
- chart:pie-donut:avoid
- lever:chart-family
- operator:part-whole
- quality:readability
advice
Choose the bar chart for share comparison
Use a bar chart when readers need to compare the sizes of shares within one total. For example, replace a pie chart with a bar chart when differences between shares are small.
reason
Why bars support share comparison better than pies
A bar chart gives each share a directly comparable length. That makes small differences easier to inspect than asking readers to compare slice sizes in a pie.
Mechanism: The chart turns the task into side-by-side length comparison, which helps readers judge which share is larger.
Evidence: The source says pie charts are not the best choice if readers need to compare the size of shares, especially when differences are small, and recommends considering a bar or column chart instead (Muth, 2018).
context
Use when the task is comparing shares within one total
- User Goal: Compare the sizes of categories that add up to a whole.
- Task: Judge which share is bigger and by how much.
- Data: One total divided into multiple shares.
- Chart Setting: Choosing between a pie chart and a bar chart.
- Success Criterion: Small differences between shares are easy to see.
exceptions
Do not use when the task is spotting landmark fractions
Break it when: The main question is whether a share is around 25%, 50%, or 75%. Why: Pie charts work better for spotting those landmark percentages.
costs
Tradeoffs of choosing the bar chart
Sacrifice: You stop showing the shares as slices of a circle. Risk: Keeping the pie chart makes close differences hard to compare. Mitigation: Switch to the bar chart when cross-category comparison is the main job.
mistakes
Common misuse of the share-comparison bar
Mistake: Keeping a pie chart for a task that asks readers to compare similarly sized shares. Why it fails: Small differences are harder to compare in a pie.
check
Check whether the bar wins this chart choice
Failure Sign: Readers struggle to tell which of two similar shares is larger. Quick Check: Draft the same data as both a pie chart and a bar chart, then compare which one makes the larger share more obvious. Stronger Test: Ask a reviewer to identify the larger of two close shares from both drafts and keep the easier version.
fix
Fix the chart choice for share comparison
- Replace the pie chart with a bar chart when the goal is comparing share sizes.
- Make the switch as soon as the differences between shares are small.
- Keep the pie chart only if the real job is spotting quarter-, half-, or three-quarter shares instead.