How to add Error bars in Excel As we have stated above, you will need to begin with an existing graph, so ensure one is created and opened before going forward.

If you create charts with Excel, error bars allow you to visualize margins of error for data points. Here's how to add error bars in Excel.

Suppose you have some data. You want to plot that data and turn it in with your lab report. Your instructor (me) told you to be sure and include error bars on your graph.