Gauge charts are tools that display a unique value within a predefined scale.
When you visit a website to check your internet speed, for example, you will likely come across an information panel where an arrow will move along a chart until it reaches the indicated speed value.
Speedtest.net gauge measuring internet speed
This is called a gauge chart. It’s an indispensable mechanism in several segments, the most common being the measurement of speed, but it can be used to measure various types of data, such as temperature.
Keep reading the post, and understand more about how it works, best practices for its correct use and a few real life examples where it can be used.
What are Gauge Charts
Gauge charts are used when there is a need to identify a single value on a predefined scale. In other words, it serves to measure the rate of change against predefined goals.
The most common representation is the round or semi round gauge, with a needle that moves according to the value on the meter reading. However, they can come in other formats as well, such as bars (horizontal) and columns (vertical).
These needles showcase information much like a reading on a dial. The value of each needle points to a number or indicator that can be easily interpreted according to its ranges.
Generally speaking, these ranges are key indicators within a range of values.
Going back to the internet speed gauge example, let’s assume that the maximum speed of the graph is 160 Mbps (value range upper limit).
If the needle moves up to 67 Mbps, it means that that indicator showed its result in a simple way and anyone can understand that the actual measured speed is 67 Mbps.
In addition to these numerical values, gauge charts can also be coded in specific color patterns, usually the same ones present at traffic lights: green is normal, yellow requires attention and red can indicate a critical state.
However, these colors may vary depending on the purpose of the chart.
The following information must be mandatorily displayed whenever you use gauge charts
Represents the series used for measurement;
Represents the defined numeric field and its unit of measurement;
Represents the movement of the needle or other gauge, serving as an indication for the measurement.
When should you use a Gauge Chart
Proper gauge charts use varies according to their type. Here are the two most commonly used cases:
Round or Semi Round (Gauge) Chart
Example of semi round gauge chart
This type of gauge chart allows you to visualize information clearly. The needle is the focal point of the chart and starts from the smallest scale of the unit of measurement up to the largest. This allows for the data to be displayed uniformly across the chart.
It is common practice to color-code the external scale of the chart to provide additional performance information.
Main applications: speedometer, temperature, volume, pressure measurements, etc.
Bar chart (horizontal) and column chart (vertical)
Example of bar chart (horizontal)
As the name suggests, these charts have horizontal and vertical layouts for ease of understanding. The information is distributed linearly, from the smallest to the largest scale.
Main applications: thermometer, volume measurements (decibels), etc.
What are the main guidelines for creating gauge charts
As gauge charts are very simple, there are few rules to follow:
- Linear – It’s mandatory for this to be linear; that is, movement from one point to another with logical and realistic intervals;
- Measurement – You can only measure one factor per chart and display a single unit of measurement;
- Unit of measurement – Must start from zero or from a point generally considered the starting point for that measurement. If it is a percentage measure, the endpoint needs to be 100%.
- Colours – Must have a logic behind them, by which ranges generally represent ranges of performance such as satisfactory, on-par and unsatisfactory.
What are the advantages of using gauge charts?
The main advantage when using gauge charts is the ease of understanding for the end user. They measure only one element and the values are simple to identify (as they usually start from the smallest to the largest).
At the same time, colour coding is intuitive and immediately interpretable by the reader.
It is often used to compare values or display an increasing or decreasing progress. It presents columns with sizes that are proportional to the values that represent them.
If you need to relay information to your team in order to accomplish a task during a meeting, this chart can help a lot.
The most common examples are speedometers, but there is a wide application spectrum for them, mainly in industrial solutions. Without a doubt, this is one of the most used chart types since its inception.
Now that you know everything there is to know about gauge charts, learn about our solutions to further improve data management for your business.
Looking for more?
Be the first to know
Get first-hand access to our free Design and Dataviz content directly in your inbox