Excel Combo Chart Example: Build a Clear Two-Axis Chart

An Excel combo chart combines two chart types—such as columns and a line—in one visual. For a practical example, plot monthly revenue as columns and conversion rate as a line on a secondary axis: select both data series, then use Insert > Insert Combo Chart > Create Custom Combo Chart in Excel for Microsoft 365 on Windows.

A Practical Combo Chart Example

Imagine a report comparing revenue with the percentage of website visitors who make a purchase. Revenue is measured in thousands of dollars, while conversion rate is a percentage. A column chart makes changes in revenue easy to compare month by month; a line shows the trend in conversion rate. Because the two measures use different scales, the line should usually use a secondary vertical axis.

Month	Revenue ($ thousands)	Conversion rate
January	120	4.2%
February	135	4.5%
March	128	4.1%
April	152	5.0%
May	161	5.3%
June	174	5.6%

In this example, revenue rises overall, with a small dip in March. Conversion also climbs overall, though it falls slightly in March. The chart lets a reader see whether the two measures move together without implying that they are measured in the same units. The values are illustrative, not a benchmark for a particular business.

Why Use a Combo Chart?

A combo chart is useful when two related series benefit from different visual forms or when their magnitudes differ substantially. Columns are effective for comparing separate periods or categories. A line is effective for emphasizing the direction of a series across an ordered sequence, such as months. Putting both in one plot can make a relationship easier to inspect than two separate charts.

Typical combinations include:

Monthly sales columns with a profit-margin line.
Units sold as columns with a target or moving average as a line.
Actual spending as columns with a budget as a line.
Website visits as columns with a conversion percentage as a line.

A combo chart does not prove that one measure causes another. In the revenue example, a rising conversion rate and rising revenue may occur at the same time, but the chart alone cannot show why. Other factors, such as traffic volume, prices, or seasonality, may also affect revenue.

Prepare the Data Before Charting

Arrange the information in a simple rectangular table. Put category labels, such as months, in the first column, and give each numeric series its own column with a clear heading. Keep the labels and values aligned by row, and avoid blank rows or merged cells inside the data range. For the example, select the three columns from the Month heading through the June row.

Check that percentages are real numeric percentage values rather than text that merely looks like a percentage. In Excel, a stored value of 4.2% is equivalent to 0.042, displayed using percentage formatting. If values were imported as text, Excel may not chart them as expected. Also check that revenue is consistently expressed in thousands; mixing dollars and thousands of dollars in one series can make the chart misleading.

Use one row for each period and one column for each measure. A table with months repeated across several rows or with explanatory notes mixed into the values can confuse Excel’s automatic chart selection. If Excel assigns months as a data series instead of category labels, the chart’s row-and-column orientation may need to be switched.

Create the Combo Chart in Excel for Windows

Select the entire data range, including its headings. In the sample, that means the Month, Revenue, and Conversion rate columns and all six monthly rows.
On the ribbon, choose Insert > Insert Combo Chart > Create Custom Combo Chart. The precise icon placement can vary with ribbon layout, but look in the Charts group on the Insert tab.
In the combo chart dialog, set Revenue to Clustered Column and Conversion rate to Line. Confirm that the month labels appear as the horizontal category axis.
Check Secondary Axis for Conversion rate. Leave Revenue on the primary axis. The preview should show columns and a line with a scale on the right for the percentage series.
Choose OK. Add a descriptive chart title, such as Monthly Revenue and Conversion Rate, and check that the legend identifies both series.

If a chart already exists, select it and use Chart Design > Change Chart Type, then choose Combo. This lets you alter the chart types and axis assignment without rebuilding the source data. On Excel for Mac, select the data and use Insert > Chart > Combo; for an existing chart, Chart Design > Change Chart Type provides the chart-type controls. Ribbon placement and dialog wording can vary somewhat by Excel release. Excel for the web has chart tools too, though some formatting controls may be more limited than in the desktop app.

Understand the Secondary Axis

The primary vertical axis in the example represents revenue, in thousands of dollars. The secondary vertical axis represents conversion rate, as a percentage. The secondary axis gives each series a scale appropriate to its own units, so a small decimal percentage is not compressed against revenue values around 120 to 174.

That extra scale needs clear labeling. A reader should be able to tell which axis belongs to which series; use a chart title, axis titles, and distinct line and column colors where useful. To add axis titles in desktop Excel, select the chart and use Chart Design > Add Chart Element > Axis Titles. Choose the primary or secondary vertical axis title as appropriate, then enter labels such as Revenue ($ thousands) and Conversion rate (%).

A secondary axis can also exaggerate or minimize a visual relationship, depending on its bounds. For instance, an axis that starts at 4% rather than 0% makes small changes in conversion appear more dramatic. That may be appropriate when the goal is to inspect variation, but the scale should be visible and chosen deliberately. Do not treat the apparent height of a line relative to a column as a direct comparison of values; the units and scales are different.

Make the Chart Easier to Read

Use formatting to clarify the comparison rather than decorate the plot. Give the line a color that contrasts with the columns, and keep the legend labels concise. If readers need exact values, add data labels selectively—for example, labels on the line or on only the latest month—rather than labeling every column and point. Too many labels can obscure trends and overlap.

Consider the following finishing checks:

Use a title that states the measures and time span.
Label both vertical axes with units, including whether revenue is shown in dollars or thousands.
Format the right axis as a percentage and choose a sensible number of decimal places.
Keep month labels in chronological order; text-sorted months can otherwise appear alphabetically.
Use a light gridline treatment, or remove unnecessary gridlines, so the data remain prominent.
Check the chart at its intended display size, especially if it will be pasted into a presentation or report.

For axis settings, right-click the relevant axis and choose Format Axis to open the formatting pane. Options include number formatting and axis bounds. Automatic bounds are often a reasonable starting point, but inspect them rather than assuming they tell the clearest story. If the right axis labels display as decimals, change their number format to Percentage; if they show an unexpected scale, confirm the underlying cells contain numeric percentages.

Common Problems and How to Fix Them

The line looks almost flat. The percentage series may be plotted on the primary revenue axis. Open Change Chart Type and assign that series to the secondary axis.
The axes or legend are reversed. In the chart-type dialog, check each series name, chart type, and secondary-axis checkbox. The checkbox applies to a series, not to the month labels.
Excel plots months as bars. The data orientation may be wrong. Select the chart and use Chart Design > Switch Row/Column, then check that months are category labels and the two measures are series.
Percentages appear as 0.04 or 0.05. The data may be correctly stored as decimals but displayed with a General number format. Format the secondary axis or source cells as Percentage.
The visual comparison seems misleading. Review the secondary-axis bounds and explain the two different units. A dual-axis chart can make two trends appear more closely matched than they are.

Also verify that the chart includes the intended data range. When new months are added below the original range, a chart may not include them if its source was a fixed range. Converting the source data to an Excel table can help charts expand as rows are added, but check the chart after adding data because the series and axis assignments should still be correct.

When to Choose Another Chart Type

A combo chart is not automatically the best choice just because a table has two measures. If both measures use the same unit and similar scale, two lines or clustered columns on one axis may be easier to interpret. If the goal is to compare separate groups rather than follow an ordered timeline, clustered bars may be clearer. If the measures are unrelated, placing them together can imply a relationship that the data do not support.

Another option is to use two aligned charts with separate axes. This takes more space, but it avoids the visual ambiguity of a secondary axis and can make each measure’s scale more prominent. A combo chart is most useful when the series share a meaningful category sequence and the reader benefits from seeing their patterns together. Choose the display based on the question the chart should answer, not simply on the availability of a chart type.

Frequently Asked Questions

How do I make a combo chart in Excel?
Select the category labels and both data series, then choose Insert > Insert Combo Chart > Create Custom Combo Chart. Assign a chart type to each series and select Secondary Axis for the series that needs a separate scale.

Can a combo chart have two lines?
Yes. Excel can combine different chart types, and a combo chart can also use two line series, including one on a secondary axis. If both lines use comparable units, one shared axis is usually easier to read.

When should I use a secondary axis?
Use one when a series has different units or a substantially different magnitude, such as a percentage alongside revenue. Label it clearly and choose its scale carefully so readers are not misled by the visual relationship.

Can I change a regular chart into a combo chart?
Yes. Select the chart and choose Chart Design > Change Chart Type, then select Combo. Set each series’ chart type and axis assignment in the dialog.

Why is the secondary axis option unavailable?
Check that the chart type supports a combo arrangement and that the chart contains multiple data series. Select an individual series in the combo chart dialog; the secondary-axis choice is assigned to a series, not to a category label.

Choose the Chart for the Question

For the revenue-and-conversion example, columns plus a line on a secondary axis make the two monthly trends visible while preserving their different units. The key is not just selecting Combo: prepare a clean data table, assign the correct chart type to each series, label both axes, and review the scales. Those checks make the chart more useful—and less likely to suggest a comparison the data cannot support.

Try it: the Percentage Formula Generator: percent of, percent change, increase and decrease, with the formula.

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Sources: Function behaviour and menu paths: Microsoft Support documentation for Excel. Method & sources

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