About Second Y Axes

A second Y axis is a Y axis drawn on the right-hand side of a chart. It can show the same axis scale as the primary Y axis or a different scale.

You can use a second Y axis with the same scale as the primary Y axis on a wide chart to help viewers interpret the data more easily.

You can use a second Y axis with a different scale than the primary Y axis to plot a series of data on a different scale. This lets you compare two dissimilar series of data on the same chart without overemphasizing the importance of the larger series.

Creating Second Y Axes

To create a second Y axis, you indicate which series should appear on the second Y axis. The second Y axis appears automatically.

To plot a series on a second Y axis and automatically create the second Y axis:

1. Select the series.
2. Choose Format Series from the context menu and click the Options tab.
3. In the Options frame, in the Plot Series on Axis dropdown listbox, select Value (Y) Axis 2.
4. Click OK or Apply.

Working With Second Y Axes

A problem with plotting different series on different Y axes is that the chart itself doesn't indicate which series corresponds to which Y axis. This can be quite confusing because the viewer can't immediately identify the values of individual data points.

To help alleviate this problem, try any or all of the following:

• On one or more series, display data point labels showing data point values. See About Data Labels.
• Assign a color to each axis, its axis labels, and grid lines. Then make the series the same color as its corresponding axis. See Changing Line Styles and Colors and Changing Fill Colors, Patterns, and Gradients.
• Make a note in the axis title or in the chart title indicating which series corresponds to which axis. See About Axis Titles and About Chart Titles.