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Sample Standard Deviation Calculator

Compute the sample standard deviation (n−1), variance, mean and detect outliers.

Related tools

All Statistics & probability tools →
Population standard deviation calculatorThe population standard deviation σ of a data set — how far the values spread from their mean when your data covers the whole group, dividing by N (not n−1). Enter the numbers and it returns σ, the variance σ², the mean and the count.Standard deviation calculatorCompute the standard deviation, variance and mean of a list.Sample Mean CalculatorCompute the sample mean, sum, count and range of a set of numbers.Average Deviation Calculator (mean absolute deviation)The average absolute deviation from the mean AND from the median — the median is the point that minimises it, which is worth seeing. Every |x − centre| is listed, and the standard deviation sits beside it for contrast: squaring makes SD react hard to a single outlier while the average deviation barely moves. The outlier preset is built to show exactly that.Quartile Deviation CalculatorCompute the semi-interquartile range and its coefficient, a spread measure that the extreme values cannot distort.Sample size calculatorFind the survey sample size needed for a population, confidence level and margin of error.Standard error calculatorCompute the standard error of the mean from a list of numbers.Mean absolute deviation (MAD) calculatorCompute the mean absolute deviation of a data set around its mean.

Sample Standard Deviation Calculator works straight from this page — free, instant, nothing to install. It sits under Statistics & probability in our catalogue, alongside Population standard deviation calculator and Standard deviation calculator.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What does Sample Standard Deviation Calculator do?

Compute the sample standard deviation (n−1), variance, mean and detect outliers.

When would I actually use this?

Summarising a dataset before drawing conclusions from it, checking whether a difference between two groups is real, and putting an interval around an estimate.

What is the most common mistake?

Reading a p-value as the probability that the hypothesis is wrong. It is the probability of seeing data at least this extreme if the null were true — a different statement, and a much weaker one.

How is Sample Standard Deviation Calculator different from Population standard deviation calculator?

They sit next to each other but answer different questions: Population standard deviation calculator is the one to open when you need it to the population standard deviation σ of a data set — how far the values spread from their mean when your data covers the whole group, dividing by N (not n−1). Enter the numbers and it returns σ, the variance σ², the mean and the count. Pick whichever matches what you're starting from — both are free.

Is there a tool for the next step?

Standard deviation calculator is the closest one after this: Compute the standard deviation, variance and mean of a list.

What else is worth having open alongside it?

Sample Mean Calculator and Average Deviation Calculator (mean absolute deviation) — they come up in the same task often enough to be worth a second tab.

Where do the figures come from?

Distributions and test statistics are computed from their standard definitions, not from a lookup table, so results carry more digits than a printed table would. The assumptions each test makes are stated with it.

Further reading

All guides →
How-toHow to Calculate Standard Deviation (Step by Step)Standard deviation measures how spread out your data is. Here's the formula, a worked example, and the difference between population and sample.ExplainerMean, Median and Mode: What's the Difference?Mean, median and mode all describe the 'middle' of your data — but answer different questions. Here's what each means, with examples and when to use which.ExplainerWhat Is a Percentile? The 90th Percentile ExplainedA percentile tells you where a value ranks within a group. Learn what the 90th percentile really means and why a percentile is not the same as a percentage.How-toHow to Calculate a Weighted AverageA weighted average gives some values more influence than others. Learn the Σ(w·x) / Σw formula with grade and portfolio examples you can follow step by step.How-toScientific Notation ExplainedScientific notation writes huge and tiny numbers as a value times a power of ten. Here's how to write it, read the exponent, and convert back.ExplainerWhat Is a Z-Score? Standard Deviations Above the MeanA z-score is z = (x − μ) / σ — how many standard deviations a value sits from the mean. Learn how to compute it, read the standard normal curve, and turn it into a percentile.