Hi I have a chart I wanted to plot data from 1 - 10 on both the x and y axis. This has worked but due to the size of the labels excel has made the range larger. I can hide all the intersecting lines most easily by making all the major grid-lines 100% transparent, but I needed to mark the half way point chopping my data plots into quarters.

I need to add a horizontal line going all the way across the chart at 5 and a vertical line going all the way up the chart from 5.

Do I really have to create a whole new series as an average and plot it to achieve this or can I just get excel to add them based on an intersection?