You can use the following formula to calculate the value of two standard deviations in Excel:

=2*STDEV(A2:A14)

This particular example calculates the value of two standard deviations for the values in the cell range **A2:A14**.

The reason you might be interested in calculating this value is because in statistics the **Empirical Rule** states that for a given dataset with a normal distribution, about 95% of all data values fall within two standard deviations of the mean.

The following example shows how to calculate two standard deviations in Excel in practice.

**Example: Calculate 2 Standard Deviations in Excel**

Suppose we have the following dataset in Excel:

We can use the following formulas in various cells to calculate the mean, the value of two standard deviations, and the values that fall two standard deviations below and above the mean:

- D1:
**=AVERAGE(A2:A14)** - D2:
**=2*STDEV(A2:A14)** - D3:
**=D1-D2** - D4:
**=D1+D2**

The following screenshot shows how to use these formulas in practice:

From the output we can see:

- The mean value of the dataset is
**77.07**. - The value of two standard deviations is
**16.03**. - The value that falls two standard deviations below the mean is
**61.0465**. - The value that falls two standard deviations above the mean is
**93.1073**.

Assuming that this sample of data is representative of the larger population it came from and that the values in this population are normally distributed, we would assume that 95% of all data values in this population fall between **61.0465** and **93.1073**.

**Note**: If you would like to instead calculate three standard deviations, simply replace the **2** in the formula in cell **E2** with a **3**.

**Additional Resources**

The following tutorials explain how to perform other common operations in Excel:

How to Plot Mean and Standard Deviation in Excel

How to Perform a Standard Deviation IF Calculation in Excel

How to Calculate Weighted Standard Deviation in Excel