Standard Deviation and Variance: What Spread Really Tells You
Why we square the deviations, when to divide by n−1, and how to read a standard deviation without over-interpreting it.
Standard Deviation Calculator
Compute standard deviation, variance, mean, sum of squares and the full five-number summary of any data set.
Standard deviation
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How to use the Standard Deviation Calculator
- Fill in each field with your own figures — the defaults are only there as an example.
- The result updates as you type, so there is no button to press.
- Check the breakdown under the main result for the supporting numbers.
- Use the copy button to take the result with you, or share the link to reload the same inputs.
Standard Deviation Calculator — frequently asked questions
Is this standard deviation calculator free to use?
Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.
How accurate is the result?
The maths is exact for the formula shown on the page. Accuracy in the real world depends on your inputs and on assumptions the formula cannot see, so treat the output as a well-grounded estimate rather than a quote.
Can I use it on my phone?
Yes. The page is responsive, weighs a few kilobytes and works offline once loaded, so it behaves the same on a phone as on a desktop.
Related reading
What people search for
This page answers each of these searches. They are the exact phrases visitors use to find the standard deviation calculator.
- population variance calculator
- sample variance calculator
About this calculator
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.
Last reviewed August 15, 2026 · Calculation runs client-side · No data collected · Report an error