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Variance Calculator

Sample and population variance, with the working for each value.

Statistics Calculators Free, no sign-up Runs in your browser

Sample is the right choice unless your numbers are the entire group.

Commas, spaces, tabs or new lines.

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Variance
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Standard deviation
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The other convention
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Mean
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Sum of squared deviations
Value by value
ValueMinus the meanSquared
StatisticSample (n-1)Population (n)

About the Variance Calculator

Variance Calculator gives both conventions at once, because which one is correct depends on what your numbers are and getting it wrong is the commonest mistake in descriptive statistics. Sample variance divides the sum of squared deviations by n-1; population variance divides by n.

The n-1 is called Bessel's correction, and it exists because a sample's mean is itself estimated from the sample. That makes the deviations slightly too small on average, so dividing by n understates the spread of the population the sample came from. Dividing by n-1 corrects for it. Use the population figure only when your numbers really are every member of the group you care about.

The value-by-value table shows the whole calculation: each deviation from the mean and each squared deviation. Squaring is what makes variance work -- it stops positive and negative deviations cancelling -- and it is also why variance is in squared units, which is the reason the standard deviation is usually quoted instead.

The page shows its working, not just its answer. Where there is a formula it is printed with your own numbers substituted in, so you can check the result rather than take it on trust -- which is the difference between a calculator you can use for something that matters and one you cannot.

Everything runs inside your browser. What you type is never uploaded, never logged and never stored, and the calculator keeps working if your connection drops after the page has loaded.

How to use the Variance Calculator

  1. Choose the figure to highlightThe fields below change to match what you pick, so only the figures that matter to your case are asked for.
  2. Enter your numbersDecimals are fine, and thousands separators are accepted and ignored.
  3. Read the variance, standard deviation and the other conventionThe figures update as you type. The Calculate button is there if you would rather press something, but nothing waits for it.
  4. Copy or check the resultCopy the summary with the copy button, or open the table to check it row by row.

Features

  • Shows variance, standard deviation, the other convention, mean and sum of squared deviations together, so you are not running it twice
  • Full value by value you can open and check
  • Updates as you type, with no button to press and no page reload
  • Copy the result in one click
  • Free, no sign-up, and it runs entirely in your browser

Who uses this tool

The variance calculator is used by writers, developers, students, marketers and anyone else who needs the job done once without installing software. Common cases include:

  • Computing variance for a statistics assignment
  • Checking a spreadsheet VAR.S or VAR.P result
  • Seeing how much the n-1 correction changes the answer
  • Getting the sum of squared deviations for a further calculation

Frequently asked questions

Sample or population?

Sample, unless your data is the whole group. Almost all real data is a sample, which is why VAR.S and the n-1 divisor are the usual defaults.

Why square the deviations?

So that deviations above and below the mean do not cancel out. Squaring also gives larger deviations more weight, which is intentional.

How does variance relate to standard deviation?

The standard deviation is the square root of the variance. It is preferred for reporting because it is in the same units as the data.

If the variance calculator is not quite what you need, these other free tools solve closely related problems, and there are 13 more in statistics calculators.

Z-Score Calculator

Z-score with percentile and tail probabilities.

Statistics Calculators Use tool

Checked and rebuilt on 2026-10-14. The method this calculator uses is described in the section above, and corrections go through the contact page.