This entry is part of the Chart Index, the reference library for the Chart Design Field Guide.
The radar chart — also called a spider, web, or polar profile — arranges multiple variables on radial axes emanating from a centre, then connects the values along the axes into a polygon. Each shape's silhouette becomes a profile — an entity's footprint across several dimensions, ready to be compared visually with other entities' silhouettes.
It is the form most often used in performance reviews, product comparison spec sheets, sports analytics, and competitive intelligence decks. It is also one of the most criticised chart types in the perceptual literature. Tufte, Few, and Cleveland have all written against it; analysts continue to use it because, despite the criticisms, it produces a striking single-entity profile that no other form matches.
What it is
A radar chart maps several quantitative variables to radial axes radiating from a common centre. Each axis runs from a minimum (at the centre) to a maximum (at the outer ring). An entity's values across these dimensions are plotted as points on the axes; the points are connected to form a polygon. Multiple entities can be plotted as overlapping polygons, but the form is most readable for one entity at a time.
Eight dimensions (Speed, Accuracy, Reliability, Coverage, Cost, Ease, Support, Maturity), each on its own axis. The polygon's shape — bulging on the speed/accuracy axes, narrower on cost — gives a one-glance characterisation of the product. The convex shape tells a story; deviations from convexity (a notch in one axis) flag weaknesses.
When to use it
Radar charts are the right choice when:
- You are creating a profile or silhouette of a single entity across several dimensions.
- The reader's question is "what is this entity's shape across multiple attributes?"
- The dimensions are comparable — same scale, same direction-of-good.
- You have 3–8 axes. Fewer than 3 and the form collapses; more than 8 becomes unreadable.
- The audience is familiar with the form or you have room to introduce it.
When not to use it
- Precise comparison across many entities. Overlapping polygons become uninterpretable past two or three.
- Heterogeneous scales. If your axes mix percentages, dollars, durations, and counts, the form's common-scale assumption breaks.
- Unordered axes. Radar charts imply that adjacent axes are related; arbitrary axis order produces meaningless shapes.
- Audiences expecting precision. Few warns against radar in business reporting because executives misread the encoding.
Design principles
Order axes deliberately
Adjacent axes in a radar chart visually correlate — the polygon's shape connects them. Group related axes (Speed and Latency adjacent; Cost and Price adjacent; soft attributes like Ease and Support adjacent). Random order produces a shape whose silhouette means nothing.
Use a single colour family
For a single entity, a single colour suffices. For multiple entities, use distinct hues but keep saturation low. Two or three overlapping polygons in pastel tones work; four or five in saturated tones become a quilt.
Normalise all axes to the same range
Every axis must run from the same minimum to the same maximum (typically 0 to 100, or 0 to 1). Mixed scales make the polygon's shape misleading. If your real data spans different ranges, explicitly normalise and document the normalisation.
Show the axes with quiet rings
Concentric polygons in the background (typically at 25%, 50%, 75%, 100% of max) provide reference rings without dominating the data polygon. Use light grey strokes; no fill.
Label axes clearly outside the radar
Axis labels sit outside the outer ring, not on top of the data polygon. Each label should be horizontal where possible (rotating labels degrades readability).
Annotate notable extremes
If the entity excels or struggles on a specific axis, mark it with a short annotation. Speed: 92, exceptional or Cost: 30, weakest dimension. The polygon shows the shape; the annotation explains the meaning.
Resist using it for time-series
Some implementations animate the polygon over time. The form is poor for trend reading — radar is for profile, not trajectory. For trends, use a line chart per dimension as small multiples.
Anatomy
A radar chart's anatomy is concentric reference rings, radial axes, a data polygon, and axis labels arranged around the perimeter. The form's reading is visual silhouette; the annotations support it.
Related types
- Parallel coordinates — the linear cousin. The same multi-dimensional comparison without the radial layout.
- Small multiples of bar charts — for the same multi-attribute display when comparison precision matters.
- Star plot — historical name for the same form.
- Polar bar / polar area — radial bars instead of a connected polygon.
- Heatmap of attributes — for matrix comparison across many entities.
Reading list
- Few, S. (2005). Keep Radar Graphs Below the Radar. The definitive critique.
- Saaty, T. (1987). The Analytic Hierarchy Process. The decision-making framework that radar charts often illustrate.
- Munzner, T. (2014). Visualization Analysis and Design. The taxonomy of profile-comparison chart forms.