Radar Charts

A radar chart (spider chart) is a chart that compares several variables at once by placing each on its own spoke radiating from a shared center. To use one, give each variable a spoke on the same scale, plot each value as a point along its spoke, and join the points into a shape. Bigger, rounder shapes mean higher, more balanced scores.

A radar chart — also known as a spider chart, star chart, or polar chart — plots several variables on separate spokes that radiate from a single center point. Each spoke is its own axis, the value on that axis is marked as a point, and the points are joined into a closed shape. The result is a compact "profile" of one thing measured across many dimensions at once, which makes radar charts a favourite for comparing multi-attribute items where the overall shape matters more than any single number.

How a radar chart works

A radar chart has four building blocks. The center is the bottom of the scale. The spokes (also called radii or axes) are the straight lines running outward from the center, one per variable. The rings (the web of concentric polygons) are the gridlines, marking equal steps such as 2, 4, 6, 8 and 10. The shape is the closed polygon formed by joining each item's values, one shape per item, distinguished by colour and named in a legend.

Imagine a wheel. Every variable you want to measure gets its own spoke, spaced evenly around the circle. The center of the wheel is the lowest value (often zero) and the outer rim is the highest. For each variable you place a point along its spoke at the right distance from the center, then connect all the points to draw an enclosed polygon. The concentric rings drawn behind the spokes act like the gridlines of a normal chart, giving you reference levels to read against.

Because every axis shares the same center, you can overlay a second or third series on the same wheel — each drawn as its own coloured shape — and compare their profiles directly. Where one shape bulges outward, that item scores higher on that variable; where it pulls in toward the center, it scores lower. The eye reads the silhouettes, which is exactly what makes the format so good for "at a glance" comparison and so risky for precise reading.

How to use a spider chart, step by step

1. Pick 3 to 8 variables that describe the items you want to compare, such as price, battery life, weight, screen quality and performance.
2. Put them on one common scale. Convert everything to the same range, for example a score from 0 to 10 or a percentage of the best possible value. Raw units with different ranges make the shape meaningless.
3. Make "higher" mean "better" on every spoke. If a lower value is better (price, weight), invert it into a score so that an outward point is always good. Otherwise readers will misjudge the shape.
4. Choose a deliberate axis order. Group related variables next to each other (all cost-related spokes together, for example) and keep the same order in every chart you compare.
5. Plot one shape per item, ideally no more than three, with distinct colours, a translucent fill and a legend.
6. Label the rings and, where values are close, add the numbers so readers do not have to estimate positions on slanted spokes.

Worked example: comparing two laptops

Suppose you score two laptops from 0 to 10 on five attributes. Lower price and lower weight have already been converted to higher scores, so outward is always better.

Drawn as a radar chart, Laptop A becomes a lopsided shape that reaches the outer ring on performance and screen but pulls in on battery, portability and value: a specialist machine. Laptop B is a rounder shape that sits outside A on three of five spokes: a balanced all-rounder. That difference in silhouette is the whole point of the chart. If the question were simply "which has the better screen, and by how much?", the table or a bar chart would answer it faster.

When to use a radar chart

• Comparing profiles across several dimensions. Rating a few products, candidates, or teams on the same set of attributes — speed, cost, quality, reliability, and so on — where you want to see strengths and weaknesses as a shape.
• A small number of items. One to three overlaid series stay readable. Beyond that the shapes overlap into a tangle.
• Variables on a common scale. Scores out of ten, percentages, or ratings that all run in the same direction work cleanly because the rings mean the same thing on every spoke.
• The pattern is the message. "This option is balanced; that one is spiky" is a takeaway a radar chart delivers instantly.

When not to use a radar chart

Radar charts attract criticism, and most of it is deserved when they are stretched past their comfort zone:

• Too many axes. With a dozen or more spokes the polygon becomes a jagged blob and the labels crowd each other. Three to about eight variables is the practical sweet spot.
• Too many series. Overlay four or five shapes and they cover one another; you can no longer tell which line belongs to which item.
• Precise comparison. People judge the length of a straight bar far more accurately than the position of a point on a slanted spoke. Small differences are easy to miss.
• Non-comparable scales. If one axis runs 0–10 and another runs 0–1,000,000, the rings are meaningless and the shape is an artefact of the scaling, not the data.

How many axes or series is too many?

There is no hard limit, but readability falls off quickly. Three spokes give a triangle that carries little information; five to eight is where radar charts shine. Beyond about ten spokes the labels collide and adjacent points blur together. For series, one shape is easiest to read, two or three is comfortable with translucent fills, and four or more usually needs to be split into small multiples, a row of small radar charts with one item each, drawn on identical axes.

How to read a radar chart

Start at the center and read outward: the further a point sits from the middle, the higher its value on that axis. Check the rings first so you know what each level represents, then trace the shape spoke by spoke. To compare overlaid series, look for where one shape sits outside the other — that is a genuine advantage on that variable — and where they cross. Pay attention to overall balance: a near-circular shape means even scores across the board, while a spiky shape means strong on a few axes and weak on others. Use the value labels for anything that looks close, because your eye will only estimate positions on the spokes.

1. Read the legend to learn which shape is which item.
2. Read the scale on the rings: what is the center value and what is the outer ring worth?
3. Go spoke by spoke, noting where each shape is furthest from and closest to the center.
4. Compare shapes: outside means higher on that variable; crossing lines mark where the leader changes.
5. Judge balance, not area: a larger area is not proportionally "better", because area grows faster than the values.

Variants

The most common variant is the filled radar, where each shape is shaded with a translucent colour so overlapping profiles are still visible — the version drawn above. A line-only radar omits the fill, which keeps several series legible when their shapes cross often. A polar area chart is a cousin in which each variable becomes a wedge whose radius (not angle) encodes the value; it looks similar but is read more like a pie. Whichever you choose, keep the axis order and scale consistent so the comparison stays honest.

Common mistakes to avoid

Make a radar chart

Ready to build one? The radar chart maker lets you name your axes, enter values for one or more series, recolour and fill the shapes, and export a PNG or SVG — free, no signup, no watermark.

Not sure a radar is the right fit? The guide to choosing a chart compares the options, and the grouped bar chart is the usual alternative when exact comparison matters more than shape.

Frequently asked questions

What is a radar chart?

A radar chart, also called a spider chart, star chart or web chart, is a chart that shows several variables for one or more items on spokes radiating from a common center. Each value is marked on its spoke and the marks are joined into a closed shape, so you can compare whole profiles at a glance.

How does a radar chart work?

Every variable gets its own spoke, spaced evenly around a circle. The center is the minimum of the scale and the outer ring is the maximum. Each value is plotted as a point on its spoke at the matching distance from the center, and the points are connected to form a polygon. Concentric rings act as gridlines for reading values.

What is a spoke in a radar chart?

A spoke is one of the straight lines running from the center of a radar chart to its outer edge. Each spoke is the axis for a single variable, such as speed or price, and the position of a point along that spoke shows the value for that variable.

How do I read a radar chart?

Check the scale on the rings first, then read each spoke from the center outward: the further a point is from the center, the higher the value. Compare overlaid shapes by finding where one sits outside the other, and judge balance by whether the shape is round or spiky. Use data labels for close values.

When is a radar chart useful?

A radar chart is useful when you compare a few items, usually one to three, across roughly three to eight variables measured on the same scale, and the overall profile matters more than exact numbers. Typical uses are product comparisons, skill assessments, performance reviews and sports player ratings.

How many axes and series are too many for a radar chart?

As a rule of thumb, more than about eight to ten spokes or more than three or four overlaid series makes a radar chart hard to read. Labels crowd together, shapes cover each other and small differences disappear. Split the data into several small radar charts or use a grouped bar chart instead.