A second axis lets you plot two data series with different scales on the same chart
When you have two sets of numbers that measure different things — say, monthly revenue in dollars and customer count in units — they often have different ranges. Plotting both on the same axis makes one series hard to read. Excel lets you add a second vertical axis (called a secondary axis) so each data series can have its own scale. The second axis appears on the right side of the chart while the first stays on the left.
This is most useful when one number is much larger than the other. For example, if revenue ranges from $50,000 to $500,000 and customer count ranges from 100 to 500, the customer line would flatten to nearly invisible on a chart with a single axis. A secondary axis solves this by giving the customer count its own scale on the right.
Key Takeaways
- Right-click the data series you want on the second axis, select "Format Data Series", and choose "Secondary Axis" to move it to the right side of the chart.
- The secondary axis automatically scales to fit the data series assigned to it, so both lines or bars remain readable.
- You can format each axis independently — change the number format, minimum and maximum values, or axis title for either side.
- A secondary axis works best with line or column charts; scatter plots and pie charts do not support this feature.
The quickest way: right-click and format
Open your chart by double-clicking it in the spreadsheet. The chart enters edit mode and a gray border appears around it. Now right-click directly on the data series you want to move to the second axis — click on one of the bars, columns, or points in that series, not on the axis itself.
A context menu appears. Select "Format Data Series" (the exact wording may vary slightly depending on your Excel version). A panel opens on the right side of the screen. Look for the "Series Options" tab or section. Scroll down until you see "Plot Series On" with two radio buttons: "Primary Axis" and "Secondary Axis". Click "Secondary Axis", then close the panel. The selected series immediately moves to the right side of the chart, and a new axis appears on the right with its own scale.
Adjusting the secondary axis scale and labels
Once the second axis exists, you can control how it looks. Right-click on the secondary axis itself (the numbers on the right edge of the chart) and select "Format Axis". A panel opens where you can set the minimum value, maximum value, and major unit (the spacing between tick marks). You can also change the number format — for example, to show currency or percentages — and add an axis title by typing in the "Axis Title" field.
The primary axis (on the left) can be formatted the same way. Right-click it and choose "Format Axis" to adjust its scale independently. This is useful if one series needs to start at zero while the other does not, or if you want different number formats on each side. For instance, you might show revenue as currency on the left axis and customer count as a whole number on the right.
When a secondary axis makes sense and when it does not
A secondary axis is most effective when you are comparing two related but differently-scaled metrics. Revenue and profit margin, temperature and humidity, or website traffic and conversion rate are good candidates. The reader can see both trends at once without one drowning out the other.
Avoid a secondary axis if the two series measure the same thing in the same units — for example, sales in January and sales in February. In that case, a single axis with both series side by side is clearer. Also avoid it if you are trying to make a weak trend look stronger than it is. A secondary axis can exaggerate small changes by zooming in on the scale, which can mislead your audience.
Changing the chart type for each series
By default, both series keep their original chart type (both columns, both lines, and so on). You can mix them — for example, show one series as columns and the other as a line. Right-click the series you want to change and select "Change Series Chart Type". A dialog box opens. Choose a different chart type for that series only, then click OK.
This is especially useful when one series is a total and the other is a percentage or rate. For example, you might display total sales as columns on the primary axis and profit margin as a line on the secondary axis. The combination makes it easy to see how margin changes as sales volume moves.
Removing the secondary axis
If you decide you do not need the second axis, right-click the series on it and select "Format Data Series". Choose "Primary Axis" to move it back to the left. If no series remains on the secondary axis, the axis disappears automatically.
You can also delete the secondary axis directly by right-clicking it and selecting "Delete". This removes the axis but leaves the data series on the chart — it will revert to the primary axis scale. Either method works depending on whether you want to keep the series visible or remove it entirely.
Frequently Asked Questions
Can I add more than two axes to a chart?
No. Excel charts support only a primary axis and one secondary axis. If you need to plot more than two data series with very different scales, consider creating separate charts or using a different visualization method.
Why does my secondary axis look wrong or have strange numbers?
Excel auto-scales the secondary axis to fit the data assigned to it. If the scale seems off, right-click the secondary axis and select "Format Axis". Manually set the minimum, maximum, and major unit values to numbers that make sense for your data.
Can I use a secondary axis with a pie chart?
No. Pie charts, doughnut charts, and scatter plots do not support secondary axes. Secondary axes work with column, bar, line, and area charts.
How do I label the secondary axis so readers know what it measures?
Right-click the secondary axis and select "Format Axis". Look for "Axis Title" and type a label that describes what the series measures — for example, "Customer Count" or "Percentage". The title appears along the right edge of the chart.