How to Add a Line to a Bar Chart in Tableau

Combining a bar chart with a line chart is one of the most effective ways to tell a clear data story on a single visualization. It's perfect for comparing a volume-based metric, like sales or website sessions, with a rate-based metric, like profit margin or conversion rate, over the same period. This article will walk you through exactly how to build this type of chart, known as a dual-axis chart, in Tableau, and share some tips to make it truly effective.

First, Why Should You Add a Line to a Bar Chart?

While you can always place two charts next to each other on a dashboard, combining them serves a specific purpose: revealing relationships between different types of data. Visual cortex magic happens when you overlay two related metrics - your brain instantly starts looking for correlations.

Imagine you're a marketing manager looking at your campaign performance. You could create two separate charts:

• A bar chart showing website sessions per day.
• A line chart showing your user conversion rate per day.

Both are useful, but by placing them side-by-side, you're forcing your audience (and yourself!) to jump back and forth visually to connect the dots. When did a spike in traffic lead to a spike in conversions? When did it not?

By placing the conversion rate line directly on top of the sessions bar chart, the relationship becomes instantly obvious. You can see precisely how your high-traffic days influenced your conversion rates, uncovering insights that might have been lost otherwise.

This technique works for all kinds of scenarios:

• eCommerce: Plotting units sold (bars) against average order value (line).
• Sales: Charting new deals closed (bars) against average deal size (line).
• Operations: Visualizing the number of support tickets resolved (bars) alongside customer satisfaction scores (line).

The goal is always to link a quantity to a quality or rate to get the full story.

Creating a Combination Chart in Tableau (Step-by-Step)

Let’s build a classic marketing combination chart: Website Sessions (bars) and Conversion Rate (line) over time. For this example, we’ll assume you have a data source connected with a date field, a dimension for campaigns, and measures for sessions and conversion rate.

Step 1: Build Your Base Bar Chart

Before you can add a line, you need a bar chart. This will be the foundation of your visualization.

1. Drag your date field (e.g., ‘Date’) onto the Columns shelf. By default, Tableau might group it by YEAR. You can right-click the pill and change it to show Month, Week, or discrete Day, depending on the level of detail you need.
2. Drag the measure you want to represent with bars (e.g., ‘Sessions’) onto the Rows shelf.

You should now have a simple bar chart showing the total sessions over your selected time frame. Easy enough!

Step 2: Add the Second Measure

Now, let's bring in the metric for our line chart.

1. Find your second measure (e.g., ‘Conversion Rate’) in the Data pane.
2. Drag it and drop it onto the Rows shelf, right next to your first measure (‘Sessions’).

At this point, Tableau will likely create two separate bar charts, one on top of the other. Don't worry, this is expected. You’ve told Tableau to show two measures, and its default is to give each its own chart.

Step 3: Create the Dual Axis

This is where the magic happens. We need to tell Tableau to combine these two charts into one view by using a second axis.

1. On the Rows shelf, locate the green pill for your second measure (‘Conversion Rate’).
2. Right-click on the pill.
3. From the dropdown menu, select Dual Axis.

Instantly, your two charts will merge into one. You'll also see that a second axis has appeared on the right side of your visualization, corresponding to the new measure.

Step 4: Adjust the Mark Types

Tableau has combined the charts, but it might not have guessed the visualization types correctly. You’ll likely see overlapping circles or two sets of bars. Now you need to explicitly tell Tableau what you want each measure to look like.

Look at your Marks card. Because you've created a dual-axis chart, you'll now see controls for All, plus an individual tab for each of your measures (e.g., 'Sessions' and 'Conversion Rate').

1. Click on the Marks card tab for your first measure (‘Sessions’). In a dropdown menu just below the tab, change the mark type from Automatic to Bar. Your bars should return.
2. Next, click on the Marks card tab for your second measure (‘Conversion Rate’). Change its mark type to Line.

You’re so close! You should now have bars and a line coexisting on the same plot.

Step 5: Synchronize the Axes!

This is the most important - and most often forgotten - step.

Look at your left and right axes. You’ll notice their scales are different. The left axis might go up to 50,000 for Sessions, while the right axis only goes up to 5% for your Conversion Rate. If you leave them unsynchronized, the chart can be extremely misleading.

1. Move your cursor over the right-hand axis (the one for your line chart).
2. Right-click anywhere on the axis.
3. Select Synchronize Axis from the dropdown menu.

Tableau will adjust both axes to a compatible scale so the data points align correctly. The visual relationship you see is now an accurate one.

Pro Tips for Better Combination Charts

You’ve successfully built the chart, but finishing well matters. A little extra polish will make your visualization clearer, more professional, and more insightful.

1. Use Color and Size Intentionally

With two charts in one, color becomes even more important. Make sure your bar and line colors have enough contrast to be easily distinguished. A common practice is to use a more muted color for the higher-volume bars and a brighter, attention-grabbing color for the line to help it stand out.

You can also adjust the thickness of your bars and line. On the Marks card for your sessions, click on Size and drag the slider to make the bars a bit wider or narrower for better visual balance.

2. Be Thoughtful with Labels and Tooltips

You don't need to label every single data point. That just creates noise. Instead, enable labels at specific moments on your line chart, like the minimum and maximum points, to draw attention to them.

Clean up your tooltips, too. When a user hovers over a data point, the tooltip should clearly list the Date, the Sessions count, and the Conversion Rate. Go to the relevant Marks card, click Tooltip, and edit the text to make it clean and easy to read.

3. Clean Up by Hiding an Axis

Once your axes are synchronized, you don't necessarily need to show both. Having two different scales on both sides can still be confusing for some audiences. Since they are now in sync, you can hide one of them without affecting the visualization!

Simply right-click on one of the axes (usually the right one) and uncheck Show Header. This gives your chart a much cleaner look while preserving the accurate data mapping.

Final Thoughts

Learning how to create a dual-axis combination chart in Tableau is a simple but powerful skill that will elevate your dashboards. By layering a metric of volume with one of quality or efficiency, you can uncover critical relationships in your data and present a more complete story in a single, well-designed view.

While mastering tools like Tableau is rewarding, we know the manual process of building charts, synchronizing axes, and constantly tweaking formats takes you away from your real job: finding insights. At Graphed , we’ve made getting answers an effortless, conversational process. Instead of needing clicks and steps, you can just ask in plain English: “Show me my website sessions vs conversion rate for the last quarter as a bar and line combo chart.” We connect directly to your marketing and sales platforms to instantly generate live, interactive dashboards, so you can skip the setup and get straight to the story your data is telling.