How to Create a Bell Curve Chart
How to Create a Bell Curve Chart
A bell curve is a plot of normal distribution of a given data set. This article describes how you can create a chart of a bell curve in Microsoft Excel.
In the following example you can create a bell curve of data generated by Excel using the Random Number Generation tool in the Analysis ToolPak. After Microsoft Excel generates a set of random numbers, you can create a histogram using those random numbers and the Histogram tool from the Analysis ToolPak. From the histogram, you can create a chart to represent a bell curve.
To create a sample bell curve, follow these steps:
1.  Start Excel.  
2.  Enter the following column headings in a new worksheet:
A1:Original B1:Average C1:Bin D1:Random E1:Histogram G1:Histogram 

3.  Enter the following data in the same worksheet:
A2: 23 B2: A3: 25 B3: STDEV A4: 12 B4: A5: 24 A6: 27 A7: 57 A8: 45 A9: 19 

4.  Enter the following formulas in the same worksheet:
B2: =AVERAGE(A2:A9) B3: B4: =STDEV(A2:A9) These formulas will generate the average (mean) and standard deviation of the original data, respectively. 

5.  Enter the following formulas to generate the bin range for the histogram:
C2: =$B$23*$B4 This generates the lower limit of the bin range. This number represents three standard deviations less than the average. C3: =C2+$B$4 This formula adds one standard deviation to the number calculated in the cell above. 

6.  Select Cell C3, grab the fill handle, and then fill the formula down from cell C3 to cell C8.  
7.  To generate the random data that will form the basis for the bell curve, follow these steps:


8.  To create a histogram for the random data, follow these steps:


9.  To create a histogram for the original data, follow these steps:


10.  Create labels for the legend in the chart by entering the following:
E14: =G1&”“&G2 E15: =E1&”“&F2 E16: =G1&”“&H2 

11.  Select the range of cells, E2:H10, on the worksheet.  
12.  On the Insert menu, click Chart.  
13.  Under Chart type, click XY (Scatter).  
14.  Under Chart subtype, in the middle row, click the chart on the right.
NOTE: Just below these 5 subtypes, the description will say “Scatter with data points connected by smoothed lines without markers.” 

15.  Click Next.  
16.  Click the Series tab.  
17.  In the Name box, delete the cell reference, and then select cell E15.  
18.  In the X Values box, delete the range reference, and then select the range E3:E10.  
19.  In the Y Values box, delete the range reference, and then select the range F3:F10.  
20.  Click Add to add another series.  
21.  Click the Name box, and then select cell E14.  
22.  Click the X Values box, and then select the range E3:E10.  
23.  In the Y Values box, delete the value that’s there, and then select the range G3:G10.  
24.  Click Add to add another series.  
25.  Click the Name box, and then select cell E16.  
26.  Click the X Values box, and then select the range E3:E10.  
27.  Click the Y Values box, delete the value that’s there, and then select the range H3:H10.  
28.  Click Finish.
The chart will have two curved series and a flat series along the xaxis. 

29.  Doubleclick the second series; it should be labeled “ Bin” in the legend.  
30.  In the Format Data Series dialog box, click the Axis tab.  
31.  Click Secondary Axis, and then click OK. 
You now have a chart that compares a given data set to a bell curve