📊Standard Deviation Calculator
Paste your numbers and instantly get population and sample standard deviation, mean, variance, count, and sum — with the full step-by-step working shown.
Free Standard Deviation Calculator Online
Need to find the standard deviation of a data set fast? Our free Standard Deviation Calculator does it the moment you paste your numbers. As a fast and reliable standard deviation calculator, it handles both population and sample standard deviation, and returns the full picture — mean, variance, count, and sum — so you get every related statistic in one place.
But it does more than a single number. See the complete step-by-step working: how the mean is found, how each deviation is squared and summed, and how the result is divided and rooted — so you understand exactly how the answer is reached, not just what it is. Paste numbers separated by commas, spaces, or new lines and it just works. Whether you're checking homework, analysing results, or learning statistics, the method is laid out clearly.
Simply paste your data to see the results instantly. No sign-up, no downloads, no limits — just clear statistics whenever you need them.
Population vs Sample Standard Deviation
Population standard deviation (σ) divides the sum of squared deviations by N — the total count of values. Use this when your data set is the entire group you care about (e.g. the heights of every student in one specific class).
Sample standard deviation (s) divides by N − 1 (Bessel's correction). Use this when your data is a sample drawn from a larger population and you want to estimate the population's standard deviation. The − 1 correction makes the estimate unbiased. When in doubt for inferential statistics, sample SD is the common choice.
See the FAQ for a deeper explanation, or the About page for details on how the working is computed.