Standard Deviation Calculator
Enter a list of numbers separated by commas or spaces to instantly see the mean, population standard deviation, sample standard deviation, variance, and count.
Mean
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Population Std Dev (σ)
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Sample Std Dev (s)
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Variance (population)
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Variance (sample)
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Count (n)
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How It Works
The mean is the sum of all values divided by the count. The variance is the average of the squared differences from the mean.
Population standard deviation uses N in the denominator (the full dataset), while sample standard deviation uses N−1 (a sample drawn from a larger population). Use the sample version when your numbers are a sample of a larger dataset, and the population version when you have the entire dataset.
All calculations update instantly as you type.
Frequently Asked Questions
Should I use population or sample standard deviation?
Use population standard deviation (σ) when your numbers represent the entire dataset. Use sample standard deviation (s) when your numbers are a sample drawn from a larger population and you want to estimate the spread of that population.
How are the numbers parsed?
You can separate numbers with commas, spaces, or newlines. Any non-numeric text between numbers is treated as a separator and ignored.
What is the difference between variance and standard deviation?
Variance is the average of squared deviations from the mean. Standard deviation is the square root of variance, expressed in the same units as the original data, which makes it easier to interpret.