The Excel STDEV function estimates the standard deviation of a population from a sample (dividing by n−1). It is a legacy name — Microsoft now recommends STDEV.S, which is identical.
Syntax
| Argument | Description | |
|---|---|---|
number1 | Required | The first value or range of the sample. |
number2, ... | Optional | Up to 254 more values or ranges. Text and logical values in references are ignored. |
How to use it
STDEV treats your data as a sample drawn from a larger population, so it divides by n−1 (Bessel's correction). Use it when the numbers are a subset, not the whole group.
If your data is the entire population, use STDEVP (divide by n) instead. The two answers differ — sample standard deviation is always the larger of the pair.
Use the modern name: =STDEV.S(...) is the supported replacement and returns the same value. The .S makes the “sample” intent explicit (vs. STDEV.P for a population).
Try it: interactive demo
Pick a STDEV example to see the formula and its result.
Practice workbook
Frequently asked questions
Is STDEV the same as STDEV.S?
STDEV.S (Excel 2010+) is the sample standard deviation (divides by n−1) and returns identical results. STDEV is kept for backward compatibility.What is the difference between STDEV and STDEVP?
Does STDEV ignore text and logical values?
Should I switch to STDEV.S?
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