Combo Charts: Examples, Best Practices, and How to Create

Combo charts allow you to visualize multiple related data series in a single view, even when those series represent different types of metrics. By combining chart types such as bars and lines, a combo chart makes it possible to compare absolute values alongside trends, targets, or rates without forcing the viewer to switch between separate visuals.

When used correctly, combo charts reduce cognitive effort and help audiences understand relationships that might otherwise be missed. When used poorly, they can confuse scale, obscure meaning, and introduce misinterpretation. The difference lies in choosing the right data, assigning chart types intentionally, and applying consistent design logic.

This guide explains what combo charts are, when to use them, how they work, and how to design them effectively. It also explores common variants, real world examples, step by step creation guidance, limitations, alternatives, and frequently asked questions.

What is a combo chart?

A combo chart, also known as a combination chart, is a single visualization that uses two or more chart types together to represent different data series. The most common form combines a bar or column chart with a line chart. Each series is plotted against the same category axis, such as time, product name, or region.

The defining characteristic of a combo chart is that each data series is matched to the chart type that best represents its meaning. Discrete values such as totals or counts are typically shown using bars or columns. Continuous values such as trends, rates, or percentages are typically shown using lines.

By placing these series together, a combo chart allows viewers to see how different metrics relate to one another in context. For example, a company might want to see monthly revenue alongside profit margin, or website traffic alongside conversion rate. Viewing these metrics together often reveals patterns that would be less obvious if each metric were shown separately.

Combo charts are especially useful when the data series differ in scale. A bar chart showing revenue in large currency values can coexist with a line showing growth rate measured as a percentage, as long as the axes are handled correctly.

When and why to use a combo chart

Combo charts are not appropriate for every situation. They are most effective when the goal is to compare related metrics across the same categories while preserving clarity.

Common use cases

Comparing magnitude and trend

‍One of the most common applications is showing absolute values alongside a trend. Monthly sales volume can be shown as bars, while the sales growth rate appears as a line. This helps answer not only how much was sold but also whether performance is improving or declining over time.

Tracking performance against a target

‍ Businesses frequently compare actual performance to a goal or benchmark. A combo chart can show actual values as bars and the target as a line. This makes it easy to identify periods that exceeded expectations and periods that fell short.

Analyzing efficiency metrics

‍In marketing and operations, volume alone does not tell the full story. A combo chart can show activity volume alongside efficiency metrics such as conversion rate, utilization rate, or defect rate. This helps distinguish growth driven by efficiency from growth driven by scale.

Comparing output and capacity

‍In manufacturing, logistics, or service delivery, combo charts can show units produced as bars and capacity limits as a line. This highlights periods of strain, underutilization, or potential bottlenecks.

When not to use a combo chart

Avoid combo charts when the data series do not share a logical relationship or a common category axis. Combining unrelated metrics creates visual noise rather than insight.

Combo charts should also be avoided when more than a few data series are required. Adding too many chart types or lines increases complexity and makes interpretation difficult. In those cases, multiple simpler charts or small multiples are usually more effective.

How combo charts work

Understanding the mechanics of combo charts helps ensure they are built and interpreted correctly.

Primary and secondary axes

Most combo charts rely on two vertical axes to accommodate different data scales.

Primary axis

‍The primary vertical axis appears on the left side of the chart. It typically represents absolute values such as totals, counts, or currency amounts. Bars or columns usually align with this axis.

Secondary axis

‍The secondary vertical axis appears on the right side of the chart. It represents rates, percentages, or other metrics with a smaller numeric range. Lines usually align with this axis.

Using separate axes allows both data series to remain readable without flattening one of them. However, it also introduces the risk of misinterpretation, which is why clear labeling is essential.

Assigning chart types to data series

Chart type selection should follow the nature of the data rather than aesthetic preference.

• Bars or columns should represent discrete quantities that are easy to compare side by side.
• Lines should represent trends, rates, or continuous change over time.

This distinction helps viewers intuitively understand what each series represents without needing extensive explanation.

Shared category axis

A combo chart must have a shared horizontal axis. This axis defines the categories that both data series have in common, such as months, regions, or product lines.

The shared axis is what enables meaningful comparison. Without it, the chart becomes a layered visual with no analytical connection.

Rendering order and layering

In most tools, bars or columns are rendered first, with lines layered on top. This ensures that the primary values remain visible while the trend overlays provide context. In some cases, transparency or markers can be used to further improve readability.

Types and variants of combo charts

Column and line combo chart

This is the most widely used combo chart. Vertical columns represent discrete values, and a line represents a trend or benchmark. It is commonly used for time based analysis such as monthly revenue with growth rate.

Bar and line combo chart

This variant uses horizontal bars instead of columns. It is useful when category labels are long or when horizontal layout improves readability. Functionally, it behaves the same as a column and line combo chart.

Bar and area combo chart

In this version, the line is replaced by an area chart. The filled area emphasizes magnitude or accumulation. Transparency is important to ensure the bars remain visible beneath the area.

Dual axis combo chart

Most effective combo charts use two vertical axes. The term highlights the use of separate scales rather than a specific visual structure. Dual axis combo charts are common when mixing currency values with percentages.

Multi series combo charts

Some combo charts include more than two data series. For example, stacked columns might show sales by region, while a line shows overall margin. This approach should be used carefully, as additional series increase cognitive load. Limiting the chart to three or four total series helps preserve clarity.

Design best practices

Use consistent and meaningful color

Color should be used intentionally to differentiate data series. Choose colors that contrast clearly and remain consistent across reports. For example, if revenue is shown in blue in one chart, it should remain blue in other charts.

Avoid using too many colors or colors that are visually similar. This reduces clarity and increases interpretation effort.

Label axes clearly

Axis labels are critical in combo charts, especially when a secondary axis is used. Each vertical axis should be labeled with both the metric name and its unit, such as revenue in dollars or margin in percent.

The horizontal axis should also be clearly labeled so the viewer understands the category or time period being shown.

Keep gridlines subtle

Gridlines should support interpretation, not dominate the visual. Light, thin gridlines are usually sufficient. In some cases, gridlines can be removed entirely if data labels are present.

Maintain consistent intervals

For time based charts, use consistent intervals such as monthly or quarterly. Irregular spacing distorts perception and undermines trust in the visualization.

Use markers on lines

Markers help line series stand out when layered over bars. They are especially useful at points where the line intersects with columns.

Avoid unnecessary decoration

Avoid three dimensional effects, heavy shadows, or decorative backgrounds. These elements add visual noise without improving comprehension.

Examples and storytelling applications

Example 1: Monthly sales and conversion rate

Columns show monthly sales revenue on the primary axis. A line shows conversion rate on the secondary axis. The shared horizontal axis represents months.

This chart helps identify whether revenue changes are driven by traffic volume, efficiency, or both. A month with high revenue but low conversion rate may indicate inefficiencies, while a high conversion rate paired with low revenue may suggest missed growth opportunities.

Example 2: Actual versus target revenue

Columns represent actual revenue, and a line represents the revenue target. Since both series use the same unit, a single vertical axis may be sufficient.

This visual makes it easy to see which periods exceeded the target and which did not. Annotations can be added to explain major deviations such as product launches or market disruptions.

Example 3: Headcount and employee satisfaction

Bars show total employee count by year, and a line shows average employee satisfaction score.

This chart helps assess whether organizational growth aligns with employee experience. A decline in satisfaction as headcount increases may signal cultural or operational issues that require attention.

How to create a combo chart

Data preparation

Start with a clean data set that includes:

• One column for categories such as months or products
• One column for the first data series
• One column for the second data series

Ensure all series align to the same categories and contain no missing values unless those gaps are intentional.

Creating a combo chart in common tools

1. Select the full data range, including headers.
2. Insert a column or bar chart.
3. Change the chart type of the second data series to a line.
4. Assign the line to the secondary axis if the scale differs.
5. Add axis titles, adjust colors, and refine labels.
   

Building combo charts for dashboards

In business intelligence platforms, like Domo, combo charts can be interactive. Filters, hover tooltips, and series toggles allow users to explore the data without cluttering the visual.

Interactive combo charts are especially effective when users need to compare performance across time periods, regions, or product categories.

Limitations and alternatives

Risk of misinterpretation

Dual axis charts can confuse viewers if axes are not clearly labeled. Viewers may incorrectly compare values across axes, which leads to faulty conclusions.

Clear labeling and restrained design reduce this risk, but it should always be considered.

When combo charts are not appropriate

If the data series do not reinforce a shared story, the chart becomes noise. Combo charts should be used only when the relationship between metrics adds insight.

Alternatives to consider

• Small multiples for comparing several similar series across consistent scales
• Separate charts with coordinated highlighting for clarity
• Scatter plots for analyzing relationships between two continuous variables

Conclusion and key takeaways about combo charts

Combo charts are a powerful visualization technique when used with intention and restraint. They allow related metrics with different scales to be viewed together, revealing relationships that might otherwise remain hidden.

To use combo charts effectively, ensure the data series share a common category axis, choose chart types that match the nature of the data, label axes clearly, and avoid unnecessary complexity.

When designed well, a combo chart can replace multiple separate visuals, reduce cognitive load, and help audiences understand not just what happened, but why it happened.

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