Standard Deviation Calculator
Calculate population and sample standard deviation, variance, and mean.
Standard Deviation Calculator
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Sample vs. Population Standard Deviation
Standard deviation measures how spread out a set of numbers is from the mean. Use population standard deviation when your data represents the entire group you care about. Use sample standard deviation when your data is a sample drawn from a larger population, it divides by (n−1) instead of n to correct for sampling bias, and is the more common choice in most real-world statistics.
Frequently Asked Questions
Which one should I use, sample or population?
Use sample standard deviation if your numbers are a subset of a larger group you're trying to draw conclusions about, this is the more common case. Use population standard deviation only if your data covers the entire group of interest.
What does a low vs high standard deviation mean?
A low standard deviation means the values are clustered close to the mean, a high standard deviation means the values are more spread out.
What's the difference between variance and standard deviation?
Variance is the average of squared differences from the mean, standard deviation is the square root of variance, which brings it back to the same units as the original data.