I usually put these values in the same table as the actual X and Y values Manually Defining Custom Error Bars Sample Data and Charts You need to put all of the individual error bar values into a range of the worksheet. However, you can individual custom error bar values to all points in a plotted series. You cannot add custom error bar values to a single point in a chart.
Both articles contained instructions for adding custom error bar values for individual points, but judging from the emails I receive, a separate article on custom error bars is needed. I’ve written about Excel chart error bars in Error Bars in Excel Charts for Classic Excel and in Error Bars in Excel 2007 Charts for New Excel.
