The axis is the measuring scale that is typically placed towards the left and bottom of your chart. Typically, there are two axes:
- The axis on the left is called the Primary Vertical Axis, and
- The axis placed at the bottom is called the Primary Horizontal Axis.
Both these axes can be seen marked in Figure 1, below.
Figure 1: Axes of a chart in PowerPoint
Two more axes can be placed for most chart types. These would be:
- The Secondary Vertical Axis towards the right side of the chart's Plot Area, and
- The Secondary Horizontal Axis above the chart.
The secondary vertical axis can be seen in Figure 1, above. The secondary horizontal axis is less commonly used, and is not shown in Figure 1.
What Are These Axes Called?
Some common terminology is used to call out these axes, as explained below:
- Both horizontal axes may be called X axes, and the vertical axes may be called Y axes.
- Additionally, horizontal axes in some chart types, such as column charts are also called category axes. Also, vertical axes in some chart types, such as column charts are called value axes.
- In bar charts, the axes are reversed. Horizontal axes are typically values axes, and vertical axes becomes the category axes. This happens because bar charts are column charts that have been rotated 90 degrees clockwise.
- In addition to X and Y axes, some chart types such as 3D charts can also have a Z axis known within the PowerPoint interface as a Depth axis. Commonly, this may sometimes be called the Series axis.
Look at Figure 2, below, where you have a typical column chart. You will see that there are only two axes available for this chart. There's one each of the horizontal and vertical axes.
Figure 2: X and Y axes in a Column chart
Do All Charts Have Axes?
To confirm how many axes your chart uses, select your chart and access the Chart Tools Layout tab of the Ribbon (Mac versions of PowerPoint call this the Chart Layout tab). Here, click the Axes button to bring up a menu, as shown in Figure 3, below. Note that two axes are displayed within this menu, as shown in Figure 3.
Figure 3: Axes menu displaying two axes
The Chart Tools Layout tab is a Contextual tab. Contextual tabs are special tabs in the Ribbon that are not visible all the time. They only make an appearance when you are working with a particular slide object which can be edited using special options.
Now, look at Figure 4, below, where we added an extra Y or secondary vertical axis placed towards the right side of the chart's Plot Area.
Figure 4: Extra Y or secondary vertical axis added
Now, access the Chart Tools Layout tab and click the Axes button. Sure enough, you will now see four axes displayed on this menu, as shown in Figure 5, below (compare with Figure 3, shown previously on this page).
Figure 5: Axes menu displaying four axes
Axes Always Show as Pairs
Note that both the horizontal and vertical axes always show up in pairs within the Axes menu. You will see both secondary axes even if you have just one visible on your chart.
Next, look at this 3D Column chart, as shown in Figure 6, below, that has a third axis in addition to the two primary axes. This third axis is not a secondary axis but a Depth axis, which is also known as Z axis or a Series axis. Depth axes typically add a third dimension in 3D charts.
Figure 6: Depth axis in a 3D Column chart
Again, when you access the Chart Tools Layout tab of the Ribbon, and click the Axes button, you will see three axes displayed on the resultant menu, as shown in Figure 7, below. Notice that the Depth Axis is now shown.
Figure 7: Depth axis within the Axes menu
Now that we have explored the different axis types available for PowerPoint charts, let us look at various elements of axes which are explained below as marked in Figure 8, below.
Figure 8: Main elements of X and Y axes
The main elements of X and Y axes are:
A. Axis Title
Most axes do not display their titles but you can add a title and also change its location. By default, the name of your axis title may show up as Axis Title, as shown in Figure 8, above. Select the text box for the axis title, and type something else to replace the text to something more descriptive and suitable. Learn more about axis titles here.
B. Axis Labels
These are labels for various categories on the horizontal (category axis). On the vertical (values) axis, the labels are the values. These are typically numbers or percentage values. Learn more about changing labels, and repositioning or hiding axis labels here.
C. Major Tick Marks
Major tick marks are the indications on an axis that show up between categories on the horizontal axis, and besides Major Unit values on the vertical axis. Learn more about Tick Marks here.
D. Major Unit
This is the value interval in the vertical axis. In our example chart shown in Figure 8, above, the Major Unit is set to 1. Learn more about changing the Major Unit of the value axis here.
10 08 01 - Chart Axes: Axes in PowerPoint (Glossary Page)