STDEV function
STDEV measures how spread out a set of numbers is, treating them as a sample of a larger group. A small result means the values sit close to the average; a large one means they vary a lot. STDEV.S is the newer name for the same calculation.
- Available in
- Every current version
- Category
- Statistical functions
- Returns
- The sample standard deviation, or #DIV/0! if there are fewer than two numbers.
- Google Sheets
- Also available in Google Sheets.
Syntax
=STDEV(number1, [number2], ...)
| Argument | Required? | What it is |
|---|---|---|
number1 | Required | The first number, cell or range in the sample. |
number2 | Optional | More numbers, cells or ranges, up to 255 in total. |
Examples
Each result below is calculated from the sample sheet by our formula engine, the same one that grades the practice.
| Cell | Formula | Result | What it shows |
|---|---|---|---|
| F2 | =STDEV(B2:B7) | 1.87 | Line A fills consistently close to 500 g |
| F3 | =STDEV(C2:C7) | 7.23 | Line B varies about four times as much |
| F4 | =AVERAGE(B2:B7)+2*STDEV(B2:B7) | 504.24 | A simple upper control limit: average plus two standard deviations |
Try it live
This is the sample sheet. Change any number or text, or edit a formula, and the results update.
Show the sample data as a table
| Bag | Line A (g) | Line B (g) | Check | Result | |
| 1 | 502 | 497 | Spread, line A | 1.87 | |
| 2 | 498 | 509 | Spread, line B | 7.23 | |
| 3 | 501 | 490 | Upper limit, line A | 504.24 | |
| 4 | 499 | 506 | |||
| 5 | 500 | 501 | |||
| 6 | 503 | 494 |
Practice STDEV
Graded instantly, then re-checked on changed data.
Which store is most consistent?
H2, calculate the sample standard deviation of Store 1's daily sales. Fill down to H4.Common mistakes
| What you see | Why, and how to fix it |
|---|---|
| #DIV/0! | The range has fewer than two numbers. A standard deviation needs at least two values. |
| The result is a little higher than another tool's | STDEV divides by n-1 (sample). If your numbers are the whole population, use STDEV.P, which divides by n. |
| The sample is smaller than you think | STDEV skips text and blanks in a range, including numbers stored as text. Check with COUNT that every value is included. |
Tips
- Compare spreads with the coefficient of variation, STDEV divided by AVERAGE, when the averages are very different.
Questions
Should I use STDEV or STDEV.P?
Use STDEV (or STDEV.S) when your data is a sample of a bigger group. Use STDEV.P when you have every value in the group.
Is STDEV the same as STDEV.S?
Yes. STDEV.S is the name introduced in Excel 2010; both give the same result.
Last reviewed October 2026. Every example result on this page is calculated live by the Spreadsheet Practice formula engine.