A standard deviation calculator measures how spread out numbers are from the mean. A lower value means data points cluster close to the average; a higher value means they are more scattered.
A standard deviation calculator measures how spread out numbers are from the mean. A lower value means data points cluster close to the average; a higher value means they are more scattered. Our standard deviation calculator is built on the same core variance calculator sample standard deviation population standard deviation and is trusted by students, professionals and everyday users who need a fast, accurate result. Because every calculation runs locally in your browser, there is no waiting, no sign-up and no limit on how often you use it.
Sample vs. Population Standard Deviation
Population standard deviation (Ļ) divides by N for complete datasets. Sample standard deviation (s) uses Bessel's correction dividing by Nā1 for statistical samples.
Variance and Sum of Squares
Variance is standard deviation squared. The calculator displays step-by-step deviations from the mean and total sum of squared differences.
Empirical Rule (68-95-99.7 Rule)
In a normal distribution, ~68% of data falls within 1 standard deviation of the mean, ~95% within 2 deviations, and ~99.7% within 3.
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