How to Add Percentages to a Chart in Excel

1. Open the Excel 2010 spreadsheet where your chart is located.
2. Click on the first cell in the empty column -- or row if your data is arranged by rows -- next to the data table that makes up your chart. Type in the name of the column or row that you want to display as percentages in your chart, followed by the word 'percentage' or simply the '%' sign.
3. Enter the following formula into the cell just below, or to the right of, your header cell:=A2/sum(A:A)Change 'A2' to the first cell in the column or row that contains the data series you want to display as percentages. Change 'A:A' to the column letter or row number of the column or row where the targeted data series is located. Press 'Enter' to complete the formula.
4. Move your mouse over the fill handle in the lower right corner of the cell with your formula in it. Click and hold the mouse button, then drag your mouse toward the end of your data table. When you reach a cell that is level with the last cell in your data table, release the mouse button. Excel fills the entire row or column with your formula.
5. Click on the column letter or row number where your formulas are located. Click the 'Home' tab, then click the drop-down arrow in the 'Number' area of the ribbon. Choose 'Percentage' from the drop-down menu. The numbers in that column or row all turn into percentages.
6. Click on the data series on your chart where you want to add your percentages, then click the 'Layout' tab at the top of the screen, followed by the 'Data Labels' button in the Labels area of the ribbon. Choose one of the four data label options available in the drop-down menu.
7. Click on the data label attached to the first data point in your chart, then click it again to edit the label. Place your cursor into the formula bar at the top of the spreadsheet. Type in a '=' sign into the formula bar, then click on the cell from the series of percentages that you created which contains the percentage for the selected data point.
8. Press 'Enter.' The percentage appears on your chart. Repeat this process for every data label on your chart.