Population of five values
values = 2, 4, 4, 4, 5, 5, 7, 9type = population
Result: σ ≈ 2.00
Standard Deviation Calculator
Calculate the standard deviation of any data set, choosing between the sample formula (n − 1) and the population formula (n). Also shows variance, mean, count, and sum. Enter numbers separated by commas, spaces, or new lines.
Enter your values and press Calculate — the result appears here.
Worked examples
Sample of three values
values = 10, 12, 23type = sample
Result: s ≈ 7.00
Frequently asked questions
What is the difference between sample and population standard deviation?
Population standard deviation (σ) divides by n and applies when your data covers every member of the group. Sample standard deviation (s) divides by n − 1 and applies when your data is a subset used to estimate the whole — it is slightly larger to avoid underestimating spread.
Why does the sample formula need at least 2 values?
Sample standard deviation divides by n − 1, so with a single value the formula divides by zero and is undefined. Population standard deviation works with one value (it is 0).
Can I enter negative numbers or decimals?
Yes. Negative numbers and decimals are supported, along with scientific notation like 1e3. Separate values with commas, spaces, or new lines.
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