How to Calculate Standard Deviations and Probabilities from Data Sets in Excel

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Last Updated: March 13, 2026

If you are looking for a quick and easy way to calculate probabilities and standard deviations from data sets, Microsoft Excel is the best way to do so. Excel is a great tool, and it makes calculating probabilities easy if you know how to do so. All it takes is knowing the specific "functions" to make the spreadsheet do what you want.

Steps

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1
Open Excel. Open a Blank Workbook in the top left corner where it says "Blank Workbook".
2
Enter your data into a column in the spreadsheet. It's easier to have the data on your computer so you can paste it into a selected cell using Ctrl+C and Ctrl+V.

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3
Calculate the mean (or average) of the data set by clicking a cell and typing in the function =AVERAGE(
4
Click on the top cell of the data set and drag down to the bottom of the list to select the entire data set, then simply click the enter key. You can also enter the cells containing the data set manually by typing in the first cell, followed by a colon, followed by the cell containing the last data entry. Example: A5:A23.
5
Calculate the Standard Deviation next by typing in the function =STDEV.S( and then selecting your data set again by highlighting it or entering it manually.
6
Select your desired "x-value". In your case, this should already be selected because this is the number you're calculating your probability off of. You are either trying to calculate the percentage above or below this number. This number should be in the range of your data set, but does not specifically need to be included in the set of numerical values.
7
Calculate the percentage of values in the data set that are below your chosen "x-value" by typing in the function =NORM.DIST(
8
Select or enter your "x-value" then type a comma. Selecting the cell containing your "x-value" is better than typing it in because then you can simply change the value in the cell, and the answer will change without having to dissect the entire equation.
9
Select the cell containing your mean/average and type another comma.
10
Select the cell containing your standard deviation and type another comma.
11
Select the TURE option below the cell you're typing in and click enter to display the result.
12
Calculate the percentage that is greater than your "x-value" by typing in the function =1- followed by selecting the cell containing the previously calculated percentage (percentage less than your "x-value"
13
Change these values to be displayed as percentage values rather than decimal values. You can do this by selecting each cell containing the percentages and clicking the percentage symbol in the Number section in the Home section of the hot bar above.