How to Use Excel to Create a Bell Curve
While it may seem simple in its concept, drawing a basic bell curve in Microsoft Excel has long been a challenge for students and business professionals alike. Of course, Excel doesn't know what shape you want charted. So if you want a bell curve chart, you first have to enter the right data. In this tutorial, we select a range of numbers corresponding to a Mean average and a Standard Deviation. After applying Excel's Normal Distribution function to those numbers, Excel gives you a perfectly-formed bell curve. While a bell curve does require quite a lot of data, Excel 2013's AutoFill feature automates must of the work for you.
Decide on a Mean and a Standard Deviation. In this example, use a Mean of 60 and a Standard Deviation of 10. To create a nicely shaped bell curve, you need to enter data that is three standard deviations below the Mean and three standard deviations above the Mean. Simply put, this means the numbers 30 to 90 in a single column.
Type "30" in cell A2 and "31" in cell A3. While it's possible to fill in the remaining numbers manually, all the way to "90" in cell A62, it's much faster to let Excel do it for you using Autofill.
Drag the cursor over cells A2 and A3 to highlight them. Right click the selected cells and select "AutoFill" from the Context menu that opens. A blue arrow appears below your selection.
Drag blue "AutoFill" arrow down to cell A62. Excel automatically fills the empty cells, giving you a list of numbers from 30 to 90.
Click cell "B2." This is where you will put the Excel function to calculate the normal distribution for the number 30 in cell A2. This function requires three values: the number in cell A2, the Mean and the Standard Deviation. You must also specify whether the result should be cumulative or not. In this case, you don't want the calculation to be cumulative, so use a value of "False." Type the following formula into cell "B2" to calculate the distribution: =NORM.DIST(A2,60,10,FALSE)
Press "Enter" after entering the function. If you entered the data properly, Excel returns a value of 0.00079155.
Fill in cells B3 to B90 using Excel's AutoFill. Right-click cell "B2," select "AutoFill" from the Context menu. The blue AutoFill arrow appears below the selected cell.
Drag the blue "AutoFill" arrow all the way down to cell B62. Excel populates each cell with the same formula used in cell B2. All of the data you need to create a bell curve is now in the worksheet.
Highlight all of the cells containing your data, from cell A2 to B62. Select a chart to illustrate your data by clicking the "Insert" menu and selecting "Recommended Charts."
Select any of the recommended charts. In this case, Excel first shows a scatter chart with straight lines and markers. You can also select a line chart or a custom column chart.
Drag the chart to where you want it to appear in the worksheet. Click the "Chart Title" and type "Bell Curve" to rename the chart.