Pie and donut charts

When to use

• Showing how a total is divided between a small number of categories (ideally 3–5, maximum 7)
• When the audience needs to understand proportions at a glance, not compare precise values
• Displaying single-question survey results where categories sum to 100% (e.g., agree/neutral/disagree)
• In summary dashboards where compact, high-level composition data is appropriate

When not to use

• Don’t use when values are similar in size — human perception struggles to distinguish small differences in arc angle; use a bar chart for precise comparisons
• Don’t use with more than 7 segments — small slices become unreadable; group minor categories into “Other”
• Don’t use to compare across multiple charts — comparing two pie charts side by side is unreliable; use a grouped bar chart instead
• Don’t use for continuous or time-based data — line or area charts are the right choice

Anatomy

• Segments — Each segment’s arc angle represents its proportion of the total. Segments should start at 12 o’clock and proceed clockwise, ordered from largest to smallest.
• Labels — Prefer direct labels adjacent to segments over a separate legend. Include the category name and percentage value. Avoid labels inside small segments.
• Centre text (donut only) — The donut centre can display a key number (e.g., total count, or the dominant category value). Keep it brief.
• Tooltip — On hover or keyboard focus, show the segment label, value, and percentage.

Variants

Pie

A full circle divided into segments. Straightforward for simple compositions. Avoid exploded or 3D variants — they distort perception of angle and area.

Donut

A pie chart with the centre removed. Preferred over pie in most cases — the hollow centre can display a summary value, and the ring format reduces visual clutter. The hole size should be 40–60% of the total diameter.

Accessibility

• Never rely on colour alone — Segment labels or data values must be displayed directly on or adjacent to each segment. A legend alone is insufficient for users with colour vision deficiencies.
• Provide a data table alternative — All pie and donut charts should be accompanied by a table listing each category, its value, and its percentage.
• Keyboard access — Each segment should be individually focusable. On focus, announce the segment label, value, and percentage of total.
• Minimum segment size — Segments representing less than 3% of the total may be too small to label or interact with. Group very small segments into “Other” and document what that includes.