By default, Microsoft Office Excel determines the minimum and maximum scale values of the vertical (value) axis (axis: A line bordering the chart plot area used as a frame of reference for measurement. The y axis is usually the vertical axis and contains data. The x-axis is usually the horizontal axis and contains categories.) when you create a chart. However, you can customize the scale to better meet your needs. When the values that are plotted in the chart cover a very large range, you can also change the vertical (value) axis to a logarithmic scale (also known as log scale).
For information about how to change the scale of other axes, see Change the scale of the horizontal (category) axis in a chart or Change the scale of the depth (series) axis in a chart.
- In a chart, click the vertical (value) axis that you want to change, or do the following to select the axis from a list of chart elements:
- Click anywhere in the chart.
This displays the Chart Tools, adding the Design, Layout, and Format tabs.
- On the Format tab, in the Current Selection group, click the arrow next to the Chart Elements box, and then click Vertical (Value) Axis.
- On the Format tab, in the Current Selection group, click Format Selection.
- Click Axis Options if it is not selected, and then do one or more of the following:
Important The following scaling options are available only when a vertical (value) axis is selected. Axis Options provides different options for a horizontal (category) axis.
Note When you change the order of the values on the vertical (value) axis from bottom to top, the category labels on the horizontal (category) axis flip from the bottom to the top of the chart. Likewise, when you change the order of the categories from left to right, the value labels flip from the left side to the right side of the chart.
- To change the value axis to logarithmic, select the Logarithmic scale check box.
Note A logarithmic scale cannot be used for negative values or zero.
- To change the display units on the value axis, in the Display units list, select the units that you want.
To show a label that describes the units, select the Show display units label on chart check box.
Tip Changing the display unit is useful when the chart values are large numbers that you want to appear shorter and more readable on the axis. For example, you can display chart values ranging from 1,000,000 to 50,000,000 as 1 to 50 on the axis and show a label that indicates that the units are expressed in millions.
- To change the placement of the axis tick marks and labels, select any of the options that you want in the Major tick mark type, Minor tick mark type, and Axis labels boxes.
- To change the point where you want the horizontal (category) axis to cross the vertical (value) axis, under Horizontal axis crosses, click Axis value, and then type the number that you want in the text box, or click Maximum axis value to specify that the horizontal (category) axis crosses the vertical (value) axis at the highest value on the axis.
Note When you click Maximum axis value, the category labels are moved to the opposite side of the chart.
- When a chart displays a secondary vertical (value) axis, you can also change the scale of that axis. For more information about displaying a secondary vertical axis, see Add or remove a secondary axis in a chart.
- XY (scatter) charts and bubble charts show values on both the horizontal (category) axis and the vertical (value) axis, while line charts show values on only the vertical (value) axis. This difference is an important factor in deciding which chart type to use. Because the scale of the line chart's horizontal (category) axis cannot be changed as much as the scale of the vertical (value) axis that is used in the xy (scatter) chart, you might consider using an xy (scatter) chart instead of a line chart if you have to change the scaling of that axis or display it as a logarithmic scale.
- After changing the scale of the axis, you may also want to change the way that the axis is formatted. For more information, see Change the display of chart axes.