This entry is part of the Chart Index, the reference library for the Chart Design Field Guide.

The sunburst is a treemap rolled into a polar coordinate system. Hierarchy goes outward from the centre; each ring is a level of the tree; each arc within a ring is a node whose angular extent is its share of the parent. The form is striking — it visualises hierarchy as a radial wheel — and it shares the treemap's strengths and weaknesses, with angle replacing area as the perceptual encoding.

It is the chart most often used when aesthetics drive form selection. A sunburst on a tile is more eye-catching than a treemap of the same data. The trade-off: angle is harder to compare precisely than area, and the outer rings — where the most leaves live — get the most space per node but lose hierarchical context to the eye.

What it is

A sunburst maps a hierarchical categorical structure to nested arcs in a polar coordinate system. The centre represents the root; each successive ring is a level deeper in the hierarchy. Each arc's angular extent is proportional to its value as a share of its parent. The outermost ring holds the leaves; the inner rings hold the containers.

File system size by directory tree/var · 4 levels · 16 GB total

Three or four levels of a directory tree, drawn as concentric rings. The eye reads the inner rings as broad categories, the outer rings as the specific contributors. The whole forms a wheel where the visual weight of each angular sector at any radius shows its share at that level.

When to use it

Sunbursts are the right choice when:

  • You have a deep hierarchy (3+ levels) and want to show all levels at once.
  • The part-to-whole relationship is the message at every level.
  • The chart will be prominent and large — sunbursts need room to breathe.
  • The audience expects an editorial or eye-catching form — dashboards for executives, public-facing displays.
  • You do not need precise comparison between specific nodes.

When not to use it

  • Precise quantitative comparison. Angle perception is poor; arc-length perception varies with radius. For accurate comparison, use a treemap or bar chart.
  • Very deep hierarchies (5+ levels). Each ring is thinner than the last; the outermost rings become unreadably thin strips.
  • Wide hierarchies at the leaf level. Hundreds of leaves produce a fringe of pixel-wide arcs around the rim. Aggregate or filter.
  • Mixed-sign data. Sunbursts require non-negative values for the part-to-whole semantics.

Design principles

Limit depth to 3–4 levels

Each additional ring eats radial space. Three levels read cleanly; four are workable; five and beyond are decorative. If the data has more levels, aggregate or use a treemap, which uses space more efficiently.

Use a hierarchical colour palette

The inner ring gets distinct hues. Each child inherits its parent's hue with a slight lightness or saturation shift. The reader follows colour to trace a branch from centre to rim. A flat categorical palette across all rings makes the hierarchy invisible.

Label only what fits

Outer-ring leaves often have room for labels; inner rings have less. Set a minimum arc length (perhaps 12 pixels) and label only arcs above that. For smaller arcs, rely on tooltips or surrounding context.

Sunburst vs. treemap — same data, two layouts
SUNBURST — RADIALTREEMAP — RECTANGULAR
Both encode hierarchical part-to-whole. The treemap uses area; the sunburst uses angle. The treemap is more precise; the sunburst is more visually distinctive.

Provide tooltips and zoom

Static sunbursts of dense data are hard to read precisely. Interactive sunbursts — hover for the value, click to zoom into a sector — turn the form from a chart into an explorer. For editorial work, design for the static reading first.

Quiet the outermost ring

The leaves tend to dominate visually because they have the most circumference. Consider thinning the outermost ring's saturation, or capping the depth at 3 levels and showing remaining detail in an adjacent panel.

Avoid the dark center

A solid filled centre wastes space and adds visual weight. Either leave it empty (a donut-style centre) or use it for a total label or title. The centre is structurally meaningless; it does not have to read as content.

Show the total

State the total in the subtitle or centre. The sunburst's part-to-whole semantics require a defined whole; without it, the percentages have no anchor.

Anatomy

The Composition of a Sunburst
SourceDirectSearchSocialEmailNewsletterPromoPaidDisplayVideoRef.PartnersTOTAL100kOUTER RING — LEAVESINNER RING — CONTAINERSCENTRE — TOTAL ANCHOR
An anatomical guide

A sunburst's anatomy is concentric rings of arcs, each ring a hierarchical level, the centre an anchor for the total. The reading task: trace radially from the centre outward to find a leaf in its context.

  • Treemap — the rectangular sibling. More precise, less visually distinctive.
  • Donut chart — degenerate sunburst with one ring.
  • Icicle chart — same hierarchy, laid out as horizontal bars per level.
  • Radial bar chart — bars in polar coordinates; different question (comparison, not hierarchy).
  • Hierarchical edge bundle — for relationships within hierarchies, not part-to-whole.

Reading list

  • Stasko, J. & Zhang, E. (2000). Focus+Context Display and Navigation Techniques for Enhancing Radial, Space-Filling Hierarchy Visualizations. The interactive sunburst foundations.
  • Shneiderman, B. (1996). The Eyes Have It: A Task by Data Type Taxonomy for Information Visualizations. The reasoning behind hierarchical displays.
  • Heer, J., Bostock, M. & Ogievetsky, V. (2010). A Tour Through the Visualization Zoo. Sunburst variants and trade-offs.