This article explains how to add a secondary axis to a chart in Excel so you can view unlike categories on the same graph. These instructions work in Excel in Microsoft 365, Excel 2021, Excel 2019 ...

Graphs in Microsoft Excel typically chart time on the horizontal axis. Time is the independent variable in most relationships and dependent variables appear on the vertical axis.

Naming Basics Best practice recommendations are to create a chart placing independent variables on the horizontal, x-axis and dependent variables on the vertical, y-axis.