When you need a second axis, and when you don't

A second axis in Excel lets you plot two data series with completely different scales on the same chart. You use it when one series ranges from 0 to 100 and another ranges from 0 to 10,000 — if you tried to plot both on a single axis, the smaller numbers would flatten into an invisible line at the bottom. The second axis gives that smaller series its own scale on the right side of the chart, so both are readable.

The catch: a second axis can make a misleading chart by accident. If you stretch one axis taller than the other, you can make a small change look dramatic or a big change look flat. Use a second axis only when the two series measure different units (revenue in dollars and customer count in people) or when they genuinely operate on different scales. Do not use it to make one trend look more important than another.

Key Takeaways

  • Right-click the data series you want to move to a second axis, select "Format Data Series", and choose "Secondary Axis" — this is the fastest route in Excel 2016 and later.
  • A second axis works best when your two series measure different units or have ranges that differ by a factor of 10 or more.
  • After adding a second axis, check that both axes start at zero or at the same proportional point, or your chart will distort the comparison.
  • The second axis label appears on the right side of the chart; you can edit it by right-clicking the axis itself and selecting "Format Axis".

The fastest way: right-click the series and move it

Open your chart and double-click it to enter edit mode. You will see your data series highlighted with small squares at each data point. Right-click directly on one of those data points — not on the axis, not on the background, but on the line or bars themselves. A menu will appear.

Click "Format Data Series". A panel will open on the right side of the screen (in Excel 2016 and later) or a dialog box will appear (in older versions). Look for an option called "Series Options" or "Axis". You will see a choice between "Primary Axis" and "Secondary Axis". Select "Secondary Axis", then close the panel. That series now has its own scale on the right side of the chart.

Click outside the chart to exit edit mode and see the result. The series you moved will now use the right-side axis, and the other series will use the left-side axis. Both axes will have their own number labels and scale.

Checking that your axes don't distort the data

After you add a second axis, look at where each axis starts. If the left axis starts at 0 and the right axis starts at 500, your chart is already misleading — a flat line on the right will look like a cliff because it is being measured against a different baseline. Both axes should start at zero, or both should start at the same proportional point (for example, both at 10% of their maximum value).

To fix this, right-click the axis you want to adjust (left or right) and select "Format Axis". In the panel that opens, find "Bounds" or "Axis Options". Set the "Minimum" value to 0 for both axes, or set them to match proportionally. For example, if your left axis goes from 0 to 1,000 and your right axis goes from 0 to 100, both start at zero and the proportions are honest.

If one series spikes to 50,000 and the other to 500, and you want both visible, it is acceptable to let them have different scales — that is the whole point of a second axis. But make sure a reader can see at a glance that the scales are different. Label each axis clearly with its unit (for example, "Revenue ($)" on the left and "Customer Count" on the right).

Labeling the axes so readers understand what they are seeing

By default, Excel labels the left axis but often leaves the right axis unlabeled or gives it a generic name. Right-click the right axis (the numbers on the right side of the chart) and select "Format Axis". Look for a field called "Axis Title" or "Title". Type a clear label that describes what that axis measures — for example, "Units Sold" or "Temperature (°F)".

Do the same for the left axis if its label is unclear. A reader should be able to glance at each axis label and understand when ready that they are measuring different things. If both axes measure the same unit, you should not have a second axis in the first place.

Moving a series back to the primary axis

If you change your mind and want to move a series back to the left axis, the process is the same. Double-click the chart to enter edit mode, right-click the data series you want to move, select "Format Data Series", and choose "Primary Axis" instead of "Secondary Axis".

When you move a series back, check the scale of the remaining axis. If one series was much larger than the other, moving the smaller series back to the primary axis might make it invisible again. In that case, a second axis was the right choice, and you should move it back to secondary.

Troubleshooting: the second axis is not appearing

If you right-click a data series and do not see a "Format Data Series" option, you may have clicked the axis itself instead of the data. Click directly on a data point — a bar, a line, or a dot — not on the background or the axis numbers. The cursor should change to a hand or crosshair when you are over a data point.

If you are using a very old version of Excel (2007 or earlier), the "Secondary Axis" option may be in a different location. Look in the "Format" menu at the top instead of right-clicking. Select "Format Data Series" from the menu, then find the "Axis" tab in the dialog box that opens.

If the second axis appears but the data series is not moving to it, make sure you selected the correct series. Each series in your chart can be moved independently. Right-click the series you want to move, not a different one.

When a second axis is the wrong choice

If both your series measure the same unit (both in dollars, both in percentages, both in hours), do not use a second axis. Instead, adjust the chart type or the data itself. You might split the data into two separate charts, or you might scale one series differently before charting (for example, dividing one by 10 so both fit on the same axis).

If you are tempted to use a second axis to make one trend look more dramatic than another, resist. That is a sign your chart is trying to tell a story that the data does not support. A honest chart shows the data as it is, even if the story is less exciting.

Frequently Asked Questions

Can I have more than two axes on one chart?

Excel does not support a third axis natively. If you need to plot three series with three different scales, you will need to create two separate charts or use a different tool. Some workarounds exist (like creating a chart in one process and embedding it in another), but they are complex and usually not worth the effort.

Why does my second axis show different numbers than the first?

That is normal and expected. Each axis has its own scale based on the data in the series it measures. If the left axis shows 0 to 1,000 and the right shows 0 to 100, that is because the left series has values up to 1,000 and the right series has values up to 100. This is the whole point of a second axis.

How do I change the color of the second axis?

Right-click the right axis (the numbers on the right side) and select "Format Axis". Look for "Line Color" or "Color" options. You can change the axis line, the tick marks, and the text color. Many people color-code the axis to match the data series it measures, so readers can see at a glance which axis goes with which line.

What if I want the second axis on the left and the primary axis on the right?

Right-click the axis you want to move and select "Format Axis". Look for an option called "Position" or "Axis Position". You can set it to "Low" (left or bottom) or "High" (right or top). This is useful if you want to emphasize one series over the other, but be aware that readers expect the primary axis on the left, so switching it may confuse them.