How to Create a Speedometer Chart in Tableau

A speedometer chart is a fantastic way to display a key performance indicator (KPI) against its target. Often called a gauge chart, it gives you and your team an instant visual read on performance - are you in the red, yellow, or green? While Tableau doesn't offer a standard speedometer chart out of the box, you can build a slick, professional-looking one with a few clever tricks. This tutorial will walk you through creating one step-by-step, using a combination of a donut chart, calculated fields, and a touch of trigonometry.

First, Why Use a Speedometer Chart?

In a world of bar charts and line graphs, the speedometer offers something unique: immediate context. It’s perfect for dashboards where you want a single, important metric to stand out. Think about it:

• Tracking sales performance against a quarterly quota.
• Monitoring website uptime against a 99.9% service level agreement (SLA).
• Visualizing project completion percentage.
• Showing a marketing team's progress towards a lead generation goal.

The visual metaphor of a car's speedometer is universally understood, making it easy for anyone, regardless of their data literacy, to quickly grasp performance. However, a quick word of advice: use them sparingly. They are best for highlighting one main KPI. If you try to build a dashboard with ten different speedometers, it can quickly become cluttered. For comparing multiple categories, a simple bar chart is often more effective.

Understanding the Assembly Plan

Before we jump into the steps, it helps to know what we're actually building. A Tableau speedometer chart is not one single object, it's an assembly of a few different components layered on top of each other:

1. The Background Dial: This is essentially a donut chart. We'll create a pie chart and then turn it into a donut chart. Crucially, we’re only going to show the top half, creating that classic semi-circle gauge shape.
2. The Needle: This part is the most creative. We will use a bit of trigonometry (don't worry, it's just copy-pasting formulas) to calculate the X and Y coordinates for the needle's tip based on your KPI value. We then plot this point and draw a line to it from the center.
3. The KPI Label: We’ll place a clear text label showing the actual KPI value in the center of the gauge for readability.

It sounds complicated, but if you follow the steps, you'll see how these pieces fit together perfectly.

Step 1: Get Your Data Ready

For this example, let's assume we are tracking sales performance. We have a simple sales figure, and our goal is $200,000.

The "trick" to building a speedometer chart is that we need a simple helper file to create the necessary paths for our chart's points. Create a new sheet in Excel or Google Sheets with just two columns: Path and Value.

This little table does two important things:

• Path: This gives us a start point (1) and an end point (181) for drawing the curve of our dial.
• Value: This sets the minimum (0) and maximum (our $200k goal) values for the gauge.

Now, open Tableau and connect to your primary data source (where your sales value lives) and this new helper file. You'll want to join them, but don't worry if there isn't a common field. A cross-join will work fine here since the helper file is so small. You can do this by setting up a relationship in the Data Source tab where you define the join clause as 1 = 1.

Step 2: Create the Bins and Calculated Fields

This is where the magic happens. We need to create a few calculated fields to translate our data into visuals.

Create the Path (bin)

First, we need to create "bins" from our 'Path' field to give Tableau the points it needs to draw a smooth arc.

1. In the Data pane, right-click on your Path field.
2. Go to Create > Bins...
3. In the dialog box, set the Size of bins to 1.
4. Click OK. You'll now have a new field called Path (bin).

The Foundational Calculated Fields

Now let's create the fields that will serve as the engine for our chart.

Go to Analysis > Create Calculated Field and create the following:

1. Index: This helps us calculate the points along our path.

INDEX() - 1

1. Percentage (Your KPI): This is where you put your metric. Replace SUM([Sales]) with whatever measure you’re trying to visualize. This calculation determines how far along the gauge your needle should go.

// Replace SUM([Sales]) with your own KPI metric SUM([Sales]) / MAX([Value])

1. X-Coordinate: The trigonometry for plotting our X-axis points. This formula converts an angle into an X position.

COS(RADIANS([Index]))

1. Y-Coordinate: The trigonometry for plotting our Y-axis points. This formula converts the same angle into a Y position.

SIN(RADIANS([Index]))

1. Color Slices: This field determines the color of the background dial segments based on your KPI's value. You can adjust the thresholds (0.5 and 0.8) to match your own business logic.

IF [Percentage] >= [Index]/180 THEN
    IF [Percentage] >= 0.8 THEN "Green"
    ELSEIF [Percentage] >= 0.5 THEN "Yellow"
    ELSE "Red"
    END
ELSE
    "Grey"
END

This calculation essentially colors the part of the dial we've "achieved" and leaves the rest grey.

Step 3: Build the Speedometer Dial

Now we’ll start building the visual itself.

1. Drag X-Coordinate to the Columns shelf and Y-Coordinate to the Rows shelf.
2. Drag Path (bin) to the Detail card on the Marks pane.
3. Change the chart type from Automatic to Polygon. You might see a strange shape, which is fine for now.
4. Right-click on X-Coordinate on the Columns shelf, select Compute Using > Path (bin).
5. Do the same for Y-Coordinate on the Rows shelf: Compute Using > Path (bin). You should now see a semi-circle.
6. Drag the Color Slices calculated field to the Color card on the Marks pane.
7. Right-click on Color Slices on the Marks shelf, select Compute Using > Path (bin).
8. Adjust the colors as you see fit. Assign Red, Yellow, Green, and a light Grey to their respective values.

You should now have a half-pie chart that's colored based on your performance. This is our background Dial!

To turn it into a Donut chart, create two more calculated fields:

Inner X

[X-Coordinate] * 0.8

Inner Y

[Y-Coordinate] * 0.8

Now, drag Inner X onto the Columns shelf next to X-Coordinate and Inner Y onto the Rows shelf next to Y-Coordinate. Right-click the second X and Y pills and select Dual Axis. Synchronize the axes to combine them, and you have your donut! Set the color of the inner circle to white.

Step 4: Create and Add the Needle

The needle requires its own set of X and Y calculations.

Needle X

IF [Percentage] >= [Index]/180 AND [Percentage] <= ([Index]+1.5)/180 THEN [X-Coordinate] END

Needle Y

IF [Percentage] >= [Index]/180 AND [Percentage] <= ([Index]+1.5)/180 THEN [Y-Coordinate] END

This code tells Tableau to draw a point only at the specific position on the arc that corresponds to our KPI percentage.

Let's add it to the view:

1. Drag your new Needle X calculation to the Columns shelf.
2. Right-click the pill and create a Dual Axis chart.
3. Do the same for Needle Y, dragging it to the Rows shelf and creating a dual axis.
4. Go to the Marks Card for the new Needle X / Needle Y axis we've added. Change the chart type to Line.
5. Drag Path (bin) onto the Path card to connect the dots and create your needle line.
6. Adjust the color and weight of the line to make it stand out. A dark grey or black often works well.
7. Finally, make sure to synchronize all your axes by right-clicking each axis and selecting 'Synchronize Axis'.

Step 5: Add Finishing Touches

Your speedometer is functional, but let's make it look clean and professional.

• Add a KPI Label: Create another dual-axis chart by adding MIN(0) to the Columns shelf. In its Marks card, drag your original KPI measure (e.g., SUM(Sales)) to the Label card. This will place the exact value right in the middle. Format the font to be large and bold.
• Hide Axes and Headers: Right-click on each axis and uncheck 'Show Header' to hide the numbers.
• Remove Grid Lines: Right-click on the chart, go to 'Format', and then under 'Lines', turn off all grid lines, zero lines, and axis rulers.
• Size and Polish: Adjust the size of the needle and the donut hole to your liking using the Size slider on their respective Marks cards. You might want to format the tooltip to provide extra detail when a user hovers over the chart.

Final Thoughts

Building a speedometer chart in Tableau is definitely more involved than creating a standard bar graph, but it's a powerful way to make your most important KPIs stand out on a dashboard. By layering a polygon chart and a line chart using dual axes and some purpose-built calculated fields, you can create a dynamic and stunning visual that everyone can understand at a glance.

While mastering these types of custom charts in Tableau is a great skill, sometimes you just need to get answers from your data without a construction project. At Graphed, we designed our platform to remove the manual build process entirely. Instead of configuring bins, writing trigonometry calculations, and managing dual axes, we enable you to get the same results by just asking a simple question. You can connect your marketing and sales data sources one time and then build reports by asking things like, "Create a gauge chart showing our progress to our $200k sales goal this quarter." Try Graphed and see how quickly you can turn raw data into actionable reports.