STDEV.S in Microsoft Excel: Sample Standard Deviation

Use STDEV.S in Microsoft Excel to estimate standard deviation from a sample, using a variance denominator of n minus one. The working example below describes daily order totals; its result is measured in orders. The official reference supports the function’s identity and purpose.

This guide separates documentation review from application testing. The expected numbers are independently calculated, not screenshots or results captured from Microsoft Excel.

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

Numeric inputs: individual numbers or cell ranges holding the observations. One range can contain many observations; a header is not a measurement.

Additional inputs: optional extra numeric values or ranges. Omit the square brackets shown in the syntax notation when entering a formula. The numeric-only examples avoid relying on text or logical-value conversion.

Use the sample measure when the observed records stand in for a larger process, period or population. More rows do not automatically make a data set a complete population: a thousand sampled tickets can still be a sample of a year’s activity. Write the intended population beside the result.

The output has the same measurement units as the input, which makes it easier to interpret than variance. It is not the average absolute distance from the mean, an uncertainty interval, or the standard error of the mean. The function also cannot correct selection bias or decide whether observations are sufficiently representative for your interpretation.

An operations workbook with one row per trading day provides the scenario. Enter the following numeric observations into A2:A9, one per row, with a header in A1. Use a spare result cell outside the input range.

Download the Microsoft Excel STDEV.S practice data (CSV). Import it into a new, blank sheet starting at A1, with a comma as the file delimiter and the header row retained. The CSV contains input values only, not formulas or native test results. Blank spacer columns place the requested position in D2 and any additional test data in column F. Keep observations numeric rather than importing them as text.

Example 1: Measure spread in the working register

=STDEV.S(A2:A9)

Expected result: 136.06721 (displayed to six decimal places).

The numeric count is 8, the mean is 300, and the sum of squared deviations is 129600. Divide by 7 (n minus one), then take the square root to return to the original measurement units.

Example 2: Check the denominator with three known numbers

=STDEV.S(2,4,6)

Expected result: 2.

The mean is 4 and the squared deviations are 4, 0 and 4, for a total of 8. The sample denominator is 2, and the square root of that variance gives standard deviation.

Example 3: Do not confuse real zeros with missing data

For this check, use F2:F5 containing 0, 0, 8, 8, in that order. These values are included in the practice file.

=STDEV.S(F2:F5)

Expected result: 4.618802 (displayed to six decimal places).

All four observations are real measurements, including both zeros. The mean is 4 and the squared deviations total 64. Excluding the zeros would leave two equal values and falsely describe this group as having no spread.

Subtract the mean from each observation and square each difference. Add the squared differences and divide by n minus one. Take the square root for standard deviation; the answer returns to the original measurement units. This mathematical definition is used to check the numbers in the examples, independently of the spreadsheet software. Keep stored results at full available precision and round only the final presentation when a report requires it. The displayed expectations above are rounded where necessary; a different number of displayed decimal places is not by itself a calculation error.

There is only one observation. Sample variance needs a denominator greater than zero, so at least two numeric observations are required. A blank report is not evidence of zero variability. Validate the numeric count first.

The result differs from a population calculation. For the same n numeric observations, sample standard deviation is population standard deviation multiplied by the square root of n/(n minus one). A different denominator is not a rounding defect.

Unexpected text or errors are mixed into the input. Review the original cells rather than assuming every application ignores the same values. Do not replace a failed calculation with zero: zero has the specific meaning that included numeric observations do not vary.

The Microsoft function reference is the source for this guide’s Excel name and purpose. The reviewed Excel help distinguishes values supplied as arguments from values inside referenced arrays or ranges. Keep imported observations numeric rather than depending on automatic conversion of text or logical values.

For the daily order workbook, keep one comparable trading day per row. Exclude a grand-total row from the statistical input; it is not another trading day. When combining weeks, check that repeated dates are legitimate records rather than duplicated imports. The formula cannot make that distinction for you.

These examples use English function names and comma-separated arguments. A workbook configured for another regional separator may require semicolons. The data addresses stay the same. Test a copied formula on a small known input after an import or file conversion; this guide is not a certification of every Excel edition or exchange format.

For the same statistical question in other programs, see STDEV.S in Google Sheets, STDEV.S in ONLYOFFICE, STDEV.S in SoftMaker PlanMaker. These links identify corresponding measures, not a guarantee that names, mixed-data rules, error codes or file conversions are identical.

MEDIAN, LARGE, SMALL, RANK.EQ, STDEV.P, VAR.S, VAR.P. Browse the Microsoft Excel function library for the other published guides.

Editorial verification: The vendor documentation was reviewed on 2026-10-12. Scope: Microsoft Excel worksheet functions; the current Microsoft help entry is the reference, not a claim about every historical edition. Three numeric examples were checked with an independent arithmetic model. No native application run was performed. Single-value population edge cases, mixed-data coercion, exact error-code parity and round-trip workbook compatibility remain untested; they are not labelled application-verified.