Standard Deviation Calculator
Free online standard deviation calculator. Compute population and sample standard deviation, variance, coefficient of variation, standard error, skewness, and kurtosis from any list of numbers. 100% client-side, no upload.
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What is Standard Deviation Calculator?
A Standard Deviation Calculator measures how spread out a set of numbers is around the mean. A low standard deviation means the values cluster tightly around the average, while a high standard deviation means they are spread over a wide range. This tool computes both population and sample standard deviation, variance, the coefficient of variation, the standard error of the mean, and the third and fourth moments (skewness and kurtosis) so you can fully characterize the shape and spread of your data. It runs entirely in your browser, so nothing is ever uploaded.
Key Benefits
- Population and sample standard deviation computed side by side
- Bessel correction (n−1) toggle for sample vs population data
- Extra dispersion metrics: variance, coefficient of variation, standard error
- Shape metrics: skewness (asymmetry) and kurtosis (tailedness)
- 100% client-side - nothing leaves your device
Common Use Cases
- •Checking the variability of test scores, prices, or measurements
- •Determining whether a dataset is a sample or a full population
- •Validating statistical assumptions before running hypothesis tests
- •Learning and teaching descriptive statistics concepts
How to Use the Standard Deviation Calculator
- Enter your numbers: Type or paste your data into the input box. Separate values with commas, spaces, semicolons, or new lines. Decimals and negatives are supported.
- Pick a dataset type: Choose Sample (n−1) if your numbers are a sample of a larger population, or Population (N) if they are the entire population. This switches the variance divisor used for the headline standard deviation.
- Read the results: The top row shows the active standard deviation, variance, mean, and count. Below it you get the alternate (population/sample) values, coefficient of variation, standard error, skewness, kurtosis, range, sum, and sum of squares.
- Copy the output: Click Copy to copy every metric as plain text, ready to paste into a report, spreadsheet, or notebook.
Key Features
- Computes population and sample standard deviation side by side
- Sample (n−1, Bessel correction) and Population (N) variance toggle
- Extra dispersion metrics: coefficient of variation, standard error, skewness, kurtosis
- Accepts commas, spaces, semicolons, or new lines as separators
- Accepts decimals and negatives; flags invalid tokens instantly
- 100% client-side - nothing is uploaded