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Estimates standard deviation based on a sample. The standard deviation is a measure of how widely values are dispersed from the average value (the mean).
Important: This function has been replaced with one or more new functions that may provide improved accuracy and whose names better reflect their usage. Although this function is still available for backward compatibility, you should consider using the new functions from now on, because this function may not be available in future versions of Excel.
For more information about the new function, see STDEV.S function.
Syntax
STDEV(number1,[number2],…)
The STDEV function syntax has the following arguments:
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Number1 Required. The first number argument corresponding to a sample of a population.
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Number2, … Optional. Number arguments 2 to 255 corresponding to a sample of a population. You can also use a single array or a reference to an array instead of arguments separated by commas.
Remarks
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STDEV assumes that its arguments are a sample of the population. If your data represents the entire population, then compute the standard deviation using STDEVP.
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The standard deviation is calculated using the «n-1» method.
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Arguments can either be numbers or names, arrays, or references that contain numbers.
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Logical values and text representations of numbers that you type directly into the list of arguments are counted.
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If an argument is an array or reference, only numbers in that array or reference are counted. Empty cells, logical values, text, or error values in the array or reference are ignored.
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Arguments that are error values or text that cannot be translated into numbers cause errors.
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If you want to include logical values and text representations of numbers in a reference as part of the calculation, use the STDEVA function.
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STDEV uses the following formula:
where x is the sample mean AVERAGE(number1,number2,…) and n is the sample size.
Example
Copy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. For formulas to show results, select them, press F2, and then press Enter. If you need to, you can adjust the column widths to see all the data.
Data |
||
---|---|---|
Strength |
||
1345 |
||
1301 |
||
1368 |
||
1322 |
||
1310 |
||
1370 |
||
1318 |
||
1350 |
||
1303 |
||
1299 |
||
Formula |
Description (Result) |
Result |
=STDEV(A3:A12) |
Standard deviation of breaking strength (27.46392) |
27.46392 |
Need more help?
Excel is used extensively for statistics and data analysis. Standard deviation is something that is used quite often in statistical calculations.
In this tutorial, I will show you how to calculate the standard deviation in Excel (using simple formulas)
But before getting into, let me quickly give you a brief overview of what standard deviation is and how it’s used.
What is Standard Deviation?
A standard deviation value would tell you how much the data set deviates from the mean of the data set.
For example, suppose you have a group of 50 people, and you are recording their weight (in kgs).
In this data set, the average weight is 60 kg, and the standard deviation is 4 kg. It means that most of the people’s weight is within 4 kg of the average weight (which would be 56-64 kg).
Now let’s interpret the standard deviation value:
- A lower value indicates that the data points tend to be closer to the average (mean) value.
- A higher value indicates that there is widespread variation in the data points. This can also be a case when there are many outliers in the data set.
Calculating Standard Deviation in Excel
While it’s easy to calculate the standard deviation, you need to know which formula to use in Excel.
There are six standard deviation formulas in Excel (eight if you consider database functions as well).
These six formulas can be divided into two groups:
- Calculating the sample standard deviation: The formulas in this category are STDEV.S, STDEVA, and STDEV
- Calculating the standard deviation for an entire population: The formulas in this category are STDEV.P, STDEVPA, and STDEVP
In almost all of the cases, you will use standard deviation for a sample.
Again in layman terms, you use the term ‘population’ when you want to consider all the datasets in the entire population. On the other hand, you use term ‘sample’ when using a population is not possible (or it’s unrealistic to do so). In such a case, you pick a sample from the population.
You can use the sample data to calculate the standard deviation and infer for the entire population. You can read a great explanation of it here (read the first response).
So. this narrows down the number of formulas to three (STDEV.S, STDEVA, and STDEV function)
Now let’s understand these three formulas:
- STDEV.S – Use this when your data is numeric. It ignores the text and logical values.
- STDEVA – Use this when you want to include text and logical values in the calculation (along with numbers). Text and FALSE are taken as 0 and TRUE is taken as 1.
- STDEV – STDEV.S was introduced in Excel 2010. Before it, the STDEV function was used. It is still included for compatibility with prior versions.
So, you can safely assume that in most of the cases, you would have to use STDEV.S function (or STDEV function if you’re using Excel 2007 or prior versions).
So now let’s see how to use it in Excel.
Using STDEV.S Function in Excel
As mentioned, STDEV.S function uses numerical values but ignores the text and logical values.
Here is the syntax of STDEV.S function:
STDEV.S(number1,[number2],…)
- Number1 – This is a mandatory argument in the formula. The first number argument corresponds to the first element of the sample of a population. You can also use a named range, single array, or a reference to an array instead of arguments separated by commas.
- Number2, … [Optional argument in the formula] You can use up to 254 additional arguments. These can refer to a data point, a named range, a single array, or a reference to an array.
Now, let’s have a look at a simple example where we calculate the standard deviation.
Example – Calculating the Standard Deviation for Weight Data
Suppose you have a data set as shown below:
To calculate the standard deviation using this data set, use the following formula:
=STDEV.S(A2:A10)
In case you’re using Excel 2007 or prior versions, you will not have the STDEV.S function. In that case, you can use the below formula:
=STDEV(D2:D10)
The above formula returns the value of 2.81, which indicates that most of the people in the group would be within the weight range 69.2-2.81 and 69.2+2.81.
Note that when I say ‘most of the people’, it refers to the normal distribution of the sample (that is 68% of the sample population is within one standard deviation from the mean).
Also, note that this is a very small sample set. In reality, you may have to do this for a bigger sample data set where you can observe normal distribution better.
Hope you found this Excel tutorial useful.
You May Also Like the Following Excel Tutorials:
- Calculating Weighted Average in Excel.
- Calculating CAGR in Excel.
- Calculate and Format Percentages in Excel.
- Calculate Age in Excel using Formulas.
- Creating a Bell Curve in Excel.
- Calculating Compound Interest in Excel.
- How to Calculate Square Root in Excel
- Calculate the Coefficient of Variation (CV) in Excel
- How to Calculate Correlation Coefficient in Excel
- How to Get Descriptive Statistics in Excel?
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Step-by-step tutorial for the STDEV functions
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This wikiHow shows you how to find the standard deviation of a dataset in Microsoft Excel. Whether you’re studying for statistics, analyzing data at work, or just researching something for fun, calculating a standard deviation is essential. And, it’s pretty easy to do in Excel! There are built-in functions for calculating the standard deviation.
Things You Should Know
- There are four functions for calculating standard deviation.
- STDEV.P and STDEV.S cover most situations. Use STDEV.P for populations and STDEV.S for samples.
- The function will calculate the standard deviation for a selected range of cells.
Steps
-
1
Enter the values you want to use. Pick a column in which you want to enter your data, then type each data value into individual cells in that column. Using Excel is a great way to organize and analyze your data.
- For example, if you select column «A» as the area in which to enter your data, you might type a number into cell A1, cell A2, cell A3, and so on.
- If needed, you can move columns in your spreadsheet to organize your data.
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2
Note this information about the different functions. There are four functions in Excel for calculating standard deviation. The functions differ in two ways:[1]
- The selected function will either calculate the standard deviation for a sample (using n — 1) or a population (using n), where n is the sample size.
- The selected function will include or exclude logical values (TRUE and FALSE) and text (numbers represented as text). TRUE is interpreted as a 1, while FALSE is 0.
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3
Choose a standard deviation function. Here are the four options for calculating standard deviation:
- STDEV.P — Finds the standard deviation of a population. This function doesn’t include logical values or text.[2]
- STDEV.S — Finds the standard deviation of a sample. This function doesn’t include logical values or text.[3]
- STDEVA — Finds the standard deviation of a sample. This function does include logical values or text.[4]
- STDEVPA — Finds the standard deviation of a population. This function does include logical values or text.[5]
- There are also two outdated functions that have been replaced by the above functions. They are still present in Excel for backward compatibility reasons, but may be phased out in future versions.
- STDEV — This function was replaced by STDEV.S. Finds the standard deviation of a sample. This function doesn’t include logical values or text.[6]
- STDEVP — This function was replaced by STDEV.P. Finds the standard deviation of a population. This function doesn’t include logical values or text.[7]
- STDEV — This function was replaced by STDEV.S. Finds the standard deviation of a sample. This function doesn’t include logical values or text.[6]
- STDEV.P — Finds the standard deviation of a population. This function doesn’t include logical values or text.[2]
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4
Click a blank cell. This should be the cell in which you want to display the standard deviation value. Doing so selects the cell.
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5
Type in the standard deviation function. In the cell you selected, enter the standard deviation function you want to use. Here is STDEV.S() as an example:
- =STDEV.S()
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6
Add your value range. To do so:
- In between the parentheses, type the letter and number of the cell containing your first data value.
- Type a colon (:)
- Type the letter and number of the last cell.
- For example, if you entered your data in column «A» from rows 1 through 10, you would have =STDEV.S(A1:A10) typed here.
- If you just want to display the standard deviation of the value of a few scattered cells such as A1, B3, and C5, you can type the cell names separated by commas (e.g., =STDEV.S(A1,B3,C5)).
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7
Press ↵ Enter. This will prompt Excel to run the formula, displaying the standard deviation of the selected cells in the formula’s cell.
- If you want to check your work, you can calculate the standard deviation by hand.
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Question
How do I use Excel to calculate 2 standard deviations?
Use =STDEV(), and put your range of values in the parentheses. This can be 2 cells or 2 values (numbers).
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The old =STDEV( ) formula doesn’t work in versions of Excel older than 2007.
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What is Standard Deviation? | STDEV.P | STDEV.S | Variance
This page explains how to calculate the standard deviation based on the entire population using the STDEV.P function in Excel and how to estimate the standard deviation based on a sample using the STDEV.S function in Excel.
What is Standard Deviation?
Standard deviation is a number that tells you how far numbers are from their mean.
1. For example, the numbers below have a mean (average) of 10.
Explanation: the numbers are all the same which means there’s no variation. As a result, the numbers have a standard deviation of zero. The STDEV function is an old function. Microsoft Excel recommends using the new STEDV.S function which produces the exact same result.
2. The numbers below also have a mean (average) of 10.
Explanation: the numbers are close to the mean. As a result, the numbers have a low standard deviation.
3. The numbers below also have a mean (average) of 10.
Explanation: the numbers are spread out. As a result, the numbers have a high standard deviation.
STDEV.P
The STDEV.P function (the P stands for Population) in Excel calculates the standard deviation based on the entire population. For example, you’re teaching a group of 5 students. You have the test scores of all students. The entire population consists of 5 data points. The STDEV.P function uses the following formula:
In this example, x1 = 5, x2 = 1, x3 = 4, x4 = 6, x5 = 9, μ = 5 (mean), N = 5 (number of data points).
1. Calculate the mean (μ).
2. For each number, calculate the distance to the mean.
3. For each number, square this distance.
4. Sum (∑) these values.
5. Divide by the number of data points (N = 5).
6. Take the square root.
7. Fortunately, the STDEV.P function in Excel can execute all these steps for you.
STDEV.S
The STDEV.S function (the S stands for Sample) in Excel estimates the standard deviation based on a sample. For example, you’re teaching a large group of students. You only have the test scores of 5 students. The sample size equals 5. The STDEV.S function uses the following formula:
In this example, x1=5, x2=1, x3=4, x4=6, x5=9 (same numbers as above), x̄=5 (sample mean), n=5 (sample size).
1. Repeat steps 1-5 above but at step 5 divide by n-1 instead of N.
2. Take the square root.
3. Fortunately, the STDEV.S function in Excel can execute all these steps for you.
Note: why do we divide by n — 1 instead of by n when we estimate the standard deviation based on a sample? Bessel’s correction states that dividing by n-1 instead of by n gives a better estimation of the standard deviation.
Variance
Variance is the square of the standard deviation. It’s that simple. Sometimes it’s easier to use the variance when solving statistical problems.
1. The VAR.P function below calculates the variance based on the entire population.
Note: you already knew this answer (see step 5 under STDEV.P). Take the square root of this result to find the standard deviation based on the entire population.
2. The VAR.S function below estimates the variance based on a sample.
Note: you already knew this answer (see step 1 under STDEV.S). Take the square root of this result to find the standard deviation based on a sample.
3. VAR and VAR.S produce the exact same result.
Note: Microsoft Excel recommends using the new VAR.S function.
How to Calculate Standard Deviation in Excel Step-by-Step (2023)
Talking about statistics, the concept of standard deviation and mean go hand in hand 🤝
Mean only gives you the average figure for a dataset. But how truly does that figure represent the individual numbers of that dataset? Standard deviation will tell you that.
Standard deviation tells more about the accuracy of a mean. And interestingly, Excel offers inbuilt functions to calculate mean and standard deviation, both.
Let’s see how these Excel functions work in the guide below. Stay tuned and download our sample workbook for this guide here to practice side by side 📩
What is the standard deviation?
Standard deviation is a measure of how much the values of the dataset deviate from the mean of that dataset 🎲
This way you know if your mean is a fair representation of the underlying dataset.
Let’s quickly see this through an example. Below are the marks of a student in different subjects 🎓
We also have the mean (average marks) and standard deviation calculated for the same.
The mean for all the marks is 52. Which tells the average marks scored in all the subjects are 52 👍
And the standard deviation of 3.41 tells that the actual marks scored by the student in most of the subjects will be 3.41 marks more or less than the mean of 52.
Pro Tip!
Standard deviation can be both, positive and negative.
The closer the standard deviation is to 0, the lesser the variability in your data 💪
For example, if the mean of a data set is 70 and the standard deviation is 5. That’s fine. It means that most of the values in the dataset are around 5 points less or more than the mean of 70.
But if the standard deviation of the same mean is 20 – this means there is too much variation in the dataset. And the mean might not be a very reliable representative of this dataset as each value of this dataset might be up to 20 points more or less than 50 🧐
Calculate standard deviation using STDEV
We know how impatient you’re getting to see the Excel standard deviation function in action. So here we go with the oldest function for calculating standard deviation in Excel.
Below is the data for some people from a small town along with their ages 🔞
Note that this is a sample drawn from the entire population of that town.
We already have the mean for this data calculated (just the simple AVERAGE function running in the background) 🗯
Using these ages, let’s now find the standard deviation for this dataset through the STDEV function.
- Write the STDEV function as follows:
= STDEV (
- Create a reference to the cells containing the numbers whose standard deviation is sought.
In our example, cell range B2:B7 contains the ages so, we are referring to the same.
= STDEV (B2:B7)
Pro Tip!
Note that there is an empty cell in the list. And the STDEV function ignores blank cells in calculating the standard deviation.
Similarly, some other things you must know about the STDEV function are 💡
- It ignores any Boolean values (TRUE or FALSE), text values, and error values in the referred cell range or array.
- However, Boolean values or text values directly written as the arguments of the function are taken into account.
- The STDEV function of Excel 2003 can process up to 30 arguments only. However, Excel 2007 and later versions can process up to 255 arguments.
- Yes, that’s it, hit ‘Enter’ now.
There you go! The standard deviation for our dataset turns out as 24.3. That’s a big number considering the mean of 48.8 😮
Why is that btw? The dataset speaks out the reason very clearly and loudly.
Our sample has people from very variable age groups.
Starting from the age of 20 to the age of 80 – the variability in the numbers is huge. The standard deviation of 24.35 tells the same that the mean of 48.8 is not a very accurate representation of the dataset.
The STDEV function is now obsolete. It is primarily available in Excel 2003 up to Excel 2019. In later versions, it is only available for compatibility purposes 👵
But don’t worry – Excel has replaced the STDEV function with two more advanced functions. The STDEV.S and the STDEV.P functions. We are going to see them both now.
Calculate standard deviation using STDEV.P
Until the above example, we were dealing with a sample from a population. But if you are dealing with the entire population, you must use the STDEV.P function.
P suffixing this function represents ‘population’ 🎪
The STDEV.P function is the successor of the STDEVP function. It offers more accuracy and is available in all Excel versions starting from Excel 2010.
We will not change the dataset for now. However, this time we will use the STDEV.P function to find the standard deviation for it.
- Write the STDEV.P function as follows:
= STDEV.P (
- Again create a reference to cells B2:B7 (that contain the ages for which the standard deviation is sought).
= STDEV.P (B2:B7)
Pro Tip!
The STDEV.P function will ignore any empty cells, logical values, or text values in the referred cell range 🔪
- Hit ‘Enter’.
This time the standard deviation is slightly different from the one we calculated above. It is 21.78.
That’s because the STDEV.P function runs the formula for population standard deviation 🧠
Yes, the standard deviation formula for sample standard deviation and population standard deviation is different. We will see them both shortly.
Calculate standard deviation using STDEV.S
And now it’s time we see the STDEV.S function. This function targets the calculation of the standard deviation for a sample.
S suffixing this function represents ‘sample’.
Let’s calculate the standard deviation of the same dataset, as above using the STDEV.S function 👇
- Write the STDEV.S function as follows:
= STDEV.S (
- Again create a reference to cells B2:B7 (that contain the ages for which the standard deviation is sought).
= STDEV.S (B2:B7)
- Hit ‘Enter’.
Hope you noticed that! The standard deviation calculated by the STDEV.S function is the same as the STDEV function – 24.35 😲
This means that both the STDEV.S and STDEV functions run on the same classic sample standard deviation formula 📝
STDEV.P vs. STDEV.S
The main difference between the STDEV.P and the STDEV.S function is the formula that runs behind them. And this is why Excel replaced the STDEV function with two different functions 😎
The STDEV.S function uses the classic sample standard deviation formula as below:
Pro Tip!
For this formula:
- x represents each value of the sample
- x̅ is the mean of all the values in the sample
- ∑ is the sum of the expression
- n is the total number of values or data p
Whereas the function STDEV.P uses the following formula:
Pro Tip!
For this formula:
- x represents each value of the population
- u is the mean of all the values in the population
- ∑ is the sum of the expression
- N is the total number of values in the sample
Did you note what’s different between both the formulas? Only the denominator 🔎
In the population standard deviation formula, the whole expression is divided by N (the number of values in the entire population).
Whereas, in the sample deviation formula, the whole expression is divided by N-1 (the number of values in the sample less 1) 👀
This is called Bessel’s correction phenomenon 🏆
For sample-based formulas, we deduct 1 from the number of values (n) to adjust the mistakes resulting from assessing a sample, and not the whole population.
That’s it – Now what?
That’s all about the statistical functions of Excel dedicated to calculating standard deviation.
We have discussed all these functions meant for calculating the standard deviation of a sample and a population. Feeling pro at calculating standard deviations?
Believe me, all these functions don’t even make a speck in Excel’s functions library. Yes, it’s that huge and full of amazing functions ⚖
If you want to master the functions of Excel, better begin with the key Excel functions.
Like the VLOOKUP, SUMIF, and IF functions (some of my top favorite Excel functions).
My 30-minute free email course will take you through them (and much more) in the shortest possible time. Click here to enroll now.
Frequently asked questions
The STDEV function is one of the oldest standard deviation functions of Excel. It is available in Excel 2003 and all later versions up to Excel 2019.
The syntax of the STDEV function reads as:
= STDEV (number1, [number2], …)
It can accept up to 255 arguments that can be numbers, references to cells, or arrays.
The standard deviation formulas in Excel include:
- STDEV | =STDEV(number1, [number2], …)
- STDEV.S | =STDEV.S(number1, [number2], …)
- STDEV.P | =STDEV.P(number1, [number2], …)
- STDEVA | =STDEVA(value1, [value2], …)
- STDEVPA | =STDEVPA(value1, [value2], …)
Kasper Langmann2023-01-27T18:12:42+00:00
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