What the tool does, how to run it, and what to expect from the result.
Standard deviation measures how far values typically sit from the mean. Find the mean, square each value’s distance from it, add those squares, divide by n (population) or n − 1 (sample) and take the square root. For 2, 4, 4, 4, 5, 5, 7, 9 the mean is 5 and the squares add up to 32: σ = √(32 ÷ 8) = 2 and s = √(32 ÷ 7) = 2.138. The table below the result shows every step.
A quick way to understand who this helps, what it solves, and where it connects next.
Students, teachers, analysts and researchers working with data.
Using the standard deviation calculator without installing anything or signing up.
Short answers for the questions people usually have before trying a utility like this.
Use the sample version (n − 1) when your numbers are a sample drawn from a bigger group, which is almost always the case in surveys and experiments. Use the population version (n) only when you have every member of the group.
STDEV.S for a sample and STDEV.P for a population. Google Sheets uses STDEV and STDEVP.
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| x | x − x̄ | (x − x̄)² |
|---|---|---|
| 2 | -3 | 9 |
| 4 | -1 | 1 |
| 4 | -1 | 1 |
| 4 | -1 | 1 |
| 5 | 0 | 0 |
| 5 | 0 | 0 |
| 7 | 2 | 4 |
| 9 | 4 | 16 |
Sample: divide by n − 1 (Bessel’s correction) when the numbers are a sample of a larger group. Matches Excel STDEV.S / VAR.S.