Standard Deviation Calculator
Compute mean, variance, and standard deviation from a list of numbers.
Standard Deviation Calculator
Live result
Mean
18
Std deviation
12.32
Variance
151.67
Count
6
What it is
Standard deviation measures how spread out a set of numbers is around the mean. Low SD = clustered, high SD = scattered.
The formula
σ = √(Σ(xi − mean)² ÷ n)
Why it matters
Understanding standard deviation calculator helps you make a better-informed decision before you commit money or time.
Worked examples
Try the example
Use the defaults above as a starting point — then adjust the inputs to match your situation.
Common pitfalls
- Double-check the units on every input — most errors come from mixing units.
- Round at the end, not in the middle of the formula.
Frequently asked questions
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