Standard Deviation Calculator
Standard deviation says how spread out numbers are around their average. Paste your numbers and pick sample or population.
- Free
- Works offline after your first visit
- Saves on this device
- No sign-up
- Updated
How it works
Find the mean, take each number's distance from it, square those, and average them. For a sample, divide by one fewer than the count. Then take the square root.
Worked example
For 8 numbers with a mean of 5, the standard deviation is 2.1381.
Questions
Sample or population?
Use population if your list is every value there is. Use sample if your list is a part of a bigger group, which is the usual case.
How do I separate my numbers?
Spaces, new lines or semicolons all work.
Why does sample give a bigger answer?
Dividing by one fewer corrects for a sample tending to look less spread out than the whole group.
More like this
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- Percent Difference CalculatorGap between two values, as a share of their average.
- Weighted Average CalculatorAverage where some values count more.
- Ratio CalculatorSimplify a ratio or find a missing term.
- Median CalculatorMiddle value of a list of numbers.