Summary

STDEV.S returns the standard deviation for a sample. Standard deviation measures how far values tend to sit from the average, so it gives you a quick sense of how tightly or loosely the sample is grouped.

The .S matters here. Use this version when your data is only a sample taken from a larger population. If your dataset already represents the full population, STDEV.P is the better fit.

Syntax

=STDEV.S(number1, [number2], ...)

You can use a range, separate cells, typed values, or a mix of them.

Arguments

• number1 - [required] The first number, range, or reference in the sample.
• number2, ... - [optional] Additional sample values or ranges.

STDEV.S vs Other Functions

Using the STDEV.S Function

If the values are packed closely around the average, the result is small. If they are spread far apart, the result is larger. That makes standard deviation useful for reading consistency, volatility, and variation in a way that the average alone cannot show.

Microsoft notes that STDEV.S assumes the data is a sample of a population. It also notes that logical values and text representations of numbers typed directly into the argument list are counted, while text and logical values inside references are ignored. Blank cells in references are ignored too.

A practical way to read the result is to compare it against the scale of the data itself. A standard deviation of 1 can be tiny in one dataset and large in another, so the number makes the most sense when you interpret it in the context of the values you are analyzing.

Example 1 - Measure spread in a sample range

This is the normal setup when you have a sample already stored in cells.

=STDEV.S(B1:B5) // Returns the sample standard deviation for the range.

Example 2 - Check a tight sample

Values that stay close together produce a smaller standard deviation.

=STDEV.S(10,11,10) // Returns a small standard deviation because the values are close.

Example 3 - Check a wide sample

When two sample values are far apart, the spread becomes much larger.

=STDEV.S(10,90) // Returns a much larger standard deviation.

Example 4 - Use it as a sample risk check

This works well when you want to summarize how stable or unstable a sample looks.

=STDEV.S(B1:B10) // Returns the sample standard deviation for the range.

Conclusion Recap

• Main job: STDEV.S measures sample standard deviation.
• Use it for samples: Choose it when the data is only part of a larger population.
• Smaller result means tighter clustering: Larger result means more spread.
• Average and spread are different: The mean tells you the center, while standard deviation tells you how far values drift around it.
• Reference behavior: Text and logical values in references are ignored.
• Related option: Use STDEV.P when you have the full population.