How to Make an Excel Chart With a Negative and Positive Axis

Numerical (Value) Axis
1. Open the Microsoft Excel 2010 file that contains the chart you want to alter.
2. Click anywhere on the chart. Select the 'Format' tab at the far-right end of the ribbon. Click the drop-down box that appears on the far-left end of the ribbon. Select your desired axis from the list. Then, choose the 'Format Selection' button located right below the drop-down box.
3. Click the radio button next to 'Fixed' under the 'Minimum' heading. Place your cursor into the text box next to this button and enter the lowest number you want displayed on your axis. Place a dash before you enter the number to signify that you are entering a negative number.
4. Press 'Enter' to close the Format Axis window. Your chart will automatically update to show the negative axis.
Text-Based (Category) Axis
5. Open the Excel 2010 spreadsheet that holds the graph you want to manipulate.
6. Click on the top cell in any empty column on your spreadsheet. Enter the lowest value that you want your chart to display on the axis in this cell. Be sure to place a dash in front of a negative number. Press 'Enter' to move down to the next cell and then enter the next value you want displayed on the axis. Since you will be manipulating a text-based axis, you will have to specify each value here, as Excel will not treat these values as numbers. Continue to add values until you have added enough to fill your entire desired axis. If you are counting up from negative numbers into positive numbers, skip zero.
7. Select anywhere on the chart that you want to change. Click the 'Design' tab at the top of the screen. Find the 'Select Data' button, which is located in the Data area of the ribbon, and click it. The Select Data Source window will appear on your screen.
8. Click the 'Edit' button under the axis you want to change. The window will minimize. Select on the letter at the top of the column where you entered your desired axis labels. Choose 'OK' twice to use these labels instead of the default ones.
9. Click the 'Layout' tab at the top of the screen. Select the drop-down box that appears in the ribbon and select the axis that you just altered. Click the 'Format Selection' button.
10. Click the radio button next to 'At Category Number' under the Vertical Axis Crosses heading. Enter a number into the text box equal to the absolute value of the lowest number on your axis, plus one. So if your axis goes down to negative five, you would enter six into this box. Click 'Close' and your vertical axis will now cross your horizontal axis at the right spot.