STDEV.S Function in Excel
Calculate sample standard deviation in Excel with STDEV.S. Learn syntax, examples, and solutions to common errors for statistical analysis in spreadsheets.
Excel
Google SheetsExcelGoogle Sheets=STDEV.S(number1, [number2], ...)Quick Answer
STDEV.S function STDEV.S function calculates the standard deviation of a sample dataset in Excel and Google Sheets. It measures how spread out numbers are from their average value, helping you understand data variability. Use the syntax `=STDEV.S(number1, [number2], ...)` where number1 is your required data range containing at least 2 values.
=STDEV.S(number1, [number2], ...)Practical Examples
Basic Sales Variance Analysis
Calculate how consistent monthly sales performance is
Quality Control Testing
Measure consistency in product manufacturing
Student Performance Analysis
Compare variability between two class sections
Investment Portfolio Volatility
Measure risk by calculating return volatility
Survey Response Consistency
Analyze how much opinions vary on a satisfaction scale
Common Errors and Solutions
Division by zero
The function received fewer than 2 numerical values. Standard deviation requires at least 2 data points to calculate variance.
Verify your range contains at least 2 numeric values. Check that cells aren't empty or contain only text. Use COUNTA to count non-empty cells before applying STDEV.S. If working with filtered data, ensure at least 2 values remain visible.
Add conditional logic to check data availability: =IF(COUNT(A1:A10)>=2, STDEV.S(A1:A10), "Insufficient data")
Example:
Wrong value type
The function received an argument that cannot be converted to a number, such as error values like #N/A, #REF!, or #NAME? within the data range.
Clean your data first by removing or fixing error values. Use IFERROR to handle errors in source data. Consider using array formulas with IF to filter out problematic values before calculating standard deviation.
Wrap source calculations in IFERROR: =STDEV.S(IFERROR(A1:A10,"")). Note that this converts errors to blanks which are then ignored.
Example:
Invalid numerical operation
All provided values are identical, resulting in zero variance. While mathematically valid (standard deviation = 0), Excel sometimes returns #NUM! in edge cases with certain calculation modes.
Check if all values in your range are the same. A standard deviation of zero is valid and indicates no variability. If this is unexpected, verify you're referencing the correct data range and that your data has been entered properly.
Use formula: =IF(COUNTA(UNIQUE(A1:A10))>1, STDEV.S(A1:A10), 0) to handle uniform datasets gracefully.
Example:
Unexpected or seemingly wrong standard deviation value
Common causes include: mixing sample and population functions (STDEV.S vs STDEV.P), including headers in the range, having hidden rows with outliers, or references including entire columns with unexpected data below visible area.
1) Verify you're using the correct function (STDEV.S for samples). 2) Check that your range excludes header rows. 3) Unhide all rows to see complete data. 4) Use specific ranges (A2:A100) instead of entire columns (A:A). 5) Visually inspect your data for outliers that legitimately increase standard deviation.
Always use specific cell ranges that exclude headers and verify with spot checks. Create a separate column to calculate individual deviations from mean to understand which values contribute most to standard deviation.
Example:
Slow calculation with large datasets
Calculating standard deviation on very large ranges (100,000+ cells) or using volatile formulas that recalculate frequently can slow down your workbook significantly.
For large datasets, consider: 1) Calculating standard deviation once and storing the result as a value rather than a formula. 2) Using Excel's Data Analysis Toolpak for one-time statistical analyses. 3) Filtering data first to reduce calculation size. 4) Breaking calculations into smaller chunks if analyzing multiple groups.
Set calculation mode to Manual (Formulas tab → Calculation Options → Manual) when working with large statistical datasets, then recalculate only when needed with F9.
Example:
Best Practices and Pro Tips
Sample Size Matters
Standard deviation becomes more reliable with larger sample sizes. With fewer than 30 data points, your standard deviation estimate may be less stable. For small samples (n<30), consider reporting both the standard deviation and the sample size to provide context. Larger samples (n>100) provide much more reliable estimates of population variability.
Combining Multiple Ranges
You can calculate standard deviation across non-contiguous ranges by listing them separately in the formula. This is useful when you have data scattered across different columns or worksheets. Excel treats all referenced ranges as one unified dataset for the calculation.
Don't Mix Samples and Populations
One of the most common mistakes is using STDEV.S when you actually have complete population data, or vice versa. Using the wrong function can lead to incorrect statistical conclusions. Remember: STDEV.S for samples (most cases), STDEV.P only when you have every single member of the population with no intent to generalize.
Outlier Detection
Use standard deviation to identify outliers using the empirical rule: values more than 2-3 standard deviations from the mean are potential outliers. Create a formula like =IF(ABS(A2-AVERAGE($A$2:$A$100))>3*STDEV.S($A$2:$A$100),"Outlier","Normal") to flag unusual values that may need investigation.
Coefficient of Variation
To compare variability between datasets with different scales or units, calculate the coefficient of variation (CV) by dividing standard deviation by the mean and multiplying by 100. This expresses variability as a percentage, making it easier to compare. For example, CV=15% means the standard deviation is 15% of the mean value.
Excel vs Sheets Compatibility
STDEV.S works identically in both Excel (2010+) and Google Sheets with the same syntax and results. For older Excel versions (2007 and earlier), use STDEV instead. In Google Sheets, STDEV and STDEV.S are equivalent and both calculate sample standard deviation. When sharing files between platforms, STDEV.S ensures consistent behavior.
Performance Optimization
When calculating standard deviation for thousands of cells or in volatile formulas that recalculate frequently, consider converting the formula to a value once calculated. Use Copy → Paste Special → Values to replace the formula with its result. This prevents unnecessary recalculation and significantly improves workbook performance, especially in large financial models or data analysis worksheets.
Error-Resistant Formulas
Make your standard deviation formulas more robust by combining with error handling and data validation. Use =IFERROR(STDEV.S(A1:A100),"Insufficient Data") to handle cases where you don't have enough values. Add data quality checks with =IF(COUNT(A1:A100)>=30, STDEV.S(A1:A100), "Need more data for reliable SD") to ensure adequate sample size.
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Example Excel formula:
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