STDEV.S Function

Excel 2010+ Statistical

The Excel STDEV.S function estimates the standard deviation of a sample — how spread out the values are — dividing by n−1 to correct for sampling.

Quick answer:

=STDEV.S({2,4,4,4,5,5,7,9}) sample standard deviation =~ 2.138

Syntax

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

Argument		Description
`number1`	Required	The first number, array, or range representing a sample of the population.
`number2, ...`	Optional	Up to 254 additional numbers, arrays, or ranges.

How to use it

STDEV.S estimates the spread of a larger population from a sample of it. It divides the sum of squared deviations by n−1 (Bessel's correction), which avoids underestimating the true spread.

=STDEV.S({2,4,4,4,5,5,7,9}) // sample spread =~ 2.138

=STDEV.P({2,4,4,4,5,5,7,9}) // population spread = 2

Because it divides by the smaller n−1, STDEV.S returns a slightly larger value than STDEV.P on the same data. STDEV.S is the square root of VAR.S.

Default to STDEV.S: most real-world data is a sample, so STDEV.S is usually the right choice. Reserve STDEV.P for when you genuinely have the entire population.

Try it: interactive demo

Live demo

Pick a STDEV.S example to see the formula and its result.

example

Result:

Practice workbook

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Frequently asked questions

What is the difference between STDEV.S and STDEV.P?

STDEV.S divides by n−1 and is for a sample of a larger population; STDEV.P divides by n and is for the entire population. STDEV.S returns a slightly larger value.

Why divide by n-1 instead of n?

Dividing by n−1 (Bessel's correction) compensates for the fact that a sample tends to underestimate the spread of the population it came from, giving an unbiased estimate.

Is STDEV.S the same as the old STDEV?

Yes. STDEV.S, introduced in Excel 2010, gives identical results to the legacy STDEV function, which remains in the Compatibility category.

Does STDEV.S count text or logical values?

No. In a range, text, logicals, and empty cells are ignored. Use STDEVA if you need text counted as 0 and TRUE/FALSE as 1/0.

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Related functions: STDEV.P · VAR.S · VAR.P · STDEVA · AVERAGE