Gauge Chart

A dial showing one value against a target — familiar, and often the wrong choice.

Also known as: gauge, dial chart, speedometer chart

A gauge is a dial with a needle: one value, a target, and an arc running from zero to some maximum. It is familiar — everyone has read a speedometer — and that familiarity is the whole of its case.

The fair case

For one number against one target, “how far to target” reads instantly, and colour bands on the arc make the state legible from across a room. Teams that track a small fixed set of goals often keep one, and their audience is used to it. Calling it always wrong is too strong.

The costs

A gauge occupies a large square to communicate one number. The same square holding four small bars, or four gauges’ worth of numbers, carries more. A needle at “87” is also harder to read precisely than the digits 87 printed beside the bar it came from.

More importantly, a gauge shows neither history nor spread. You cannot tell from a gauge whether 87 is the best week of the quarter or whether the number has been flat for six months. If the question is “are we improving”, a sparkline beside the number answers it in less space.

Practical guidance

Use a gauge when the audience is used to them, there are only a few, and the question really is “are we on target”. Replace it with a number plus a target bar, or a small multiples row of bars, when the question is anything else.

Choosing which numbers deserve a dial at all is kpi design; where the dial sits on the page is dashboard design. The general case for picking a form is chart selection.