Online Tool Store
Variance Calculator
Paste a list of numbers to calculate the count, mean, sample or population variance, and standard deviation with a clear results summary.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Example shown — replace it with your own dataset.
- Count (n)
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- Mean
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- Variance
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- Std. deviation
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How Variance Calculator works
- Enter numbers separated by commas, spaces, or new lines.
- Choose whether your data represents a sample or the full population.
- Review the count, mean, variance, and standard deviation in the results summary.
The formula
Mean (x̄) = Σx ÷ n Population variance = Σ(x − x̄)² ÷ n Sample variance = Σ(x − x̄)² ÷ (n − 1) Standard deviation = √variance
FAQ
What is the difference between sample and population variance?
Population variance divides by n (the total count) because you have every data point. Sample variance divides by n − 1 (Bessel's correction) because a sample tends to underestimate the true spread otherwise — use "sample" unless your numbers really are the entire population.
How does the calculator get standard deviation?
The square root of variance. It puts the spread back into the same units as your original numbers, which is why it's usually easier to interpret than variance itself.
How many numbers do I need?
At least 2 for sample variance (dividing by n − 1 needs n ≥ 2), or 1 for population variance, though a meaningful spread calculation really needs several data points.
Is my data uploaded anywhere?
No — every calculation happens locally in your browser. Nothing is sent to a server.
How we compare
| Feature | Online Tool Store | Spreadsheet formulas | Scientific calculator |
|---|---|---|---|
| Sample and population toggle | ✓ | Two separate functions to remember | Menu diving required |
| No spreadsheet needed | ✓ | Requires Excel/Sheets | ✓ |
| Paste a whole list at once | ✓ | ✓ | Enter numbers one at a time |
For a quick homework check or a sanity check on a dataset, this beats opening a spreadsheet or typing numbers one by one into a calculator.