How to create a Vertical biaxial bar chart

A Vertical biaxial bar chart displays two different bar series on the same X-axis. It’s designed to help compare two different measured quantities over time—each with its own independent Y-axis.

When to use a Vertical biaxial bar chart

This format is ideal when you need to:

• Visualise two related metrics with different units or scales (e.g. number of participants vs average hours of engagement), using bars for both.

• Compare absolute values side by side while maintaining separate Y-axes for clarity.

• Provide a clear, direct comparison of how two distinct measures behave across the same categories or time intervals.

How to build a Vertical biaxial bar chart

Step 1: Select the Chart Type

• In the Explore Data tool, go to the Build Your Chart step.

• Under the Type tab, select Vertical biaxial bar.

  

Note: The Vertical biaxial bar chart option will be unavailable if any of the following conditions are present:

1. You have selected a mix of:
   1. Result tables (tables created directly from raw data queries, without calculations), and
   2. Calculation tables (tables generated by applying calculations to result tables ).
2. You have selected only one table, and it is a “calculation” table.
3. You have selected only “result” tables, but:
   1. The chart legend does not include “Measured quantity”, or
   2. The legend includes more than one variable, or
   3. The “Measured quantity” variable has fewer than two categories, or
   4. Tables do not have the same multi-category variables in rows.

Step 2: Create Vertical biaxial bar charts

• Navigate to the Chart tab.
• Select the tables you want to chart by toggling them on.
  
  • When working with "calculation" tables, ensure that at least two tables are selected for the chart.
  
• The Legend should contain only the Measured quantity variable.

• Configure the settings for both the left and right axes, then click Apply to update your chart.

  • When creating biaxial charts from result tables, first select the table, then choose Measured quantity for both axes. For a single result table, only the Measured quantity selection is required.

    
  • When creating charts from calculation tables, simply select the tables for both axes.
    

Step 3: Configure Y-Axis

Vertical biaxial bar charts use two Y-axes:

• Left Y-axis for the left Bar.

• Right Y-axis for the right Bar.

To customise them:

• Go to the Custom tab.
• Set the Y-axis titles:
  • Vertical Axis Title → for left Bar chart.
  • Secondary Vertical Axis Title → for right Bar chart.

• Set the value type for each axis individually:
  • Choose between Percentage or Decimal for each Y-axis.

Here is an example of a Vertical biaxial bar chart:

When you hover over the chart, a tooltip will appear showing both bar values for that X-axis category.