Standard Deviation Calculator
Enter values to calculate standard deviation with a clear result.
Calculate
Enter values and select Calculate.
How it works
Population standard deviation = square root of (sum of squared differences from the mean ÷ number of values). Sample standard deviation uses number of values minus one.
Worked examples
- 2, 4, 6: Population standard deviation 1.6330
- 5, 5, 5: Population standard deviation 0
Frequently asked questions
Is this calculator free?
Yes. You can use it without paying or creating an account.
Does it work on a phone?
Yes. The page adapts to small and large screens.
Can I enter zero?
Where zero is mathematically valid, the calculator accepts it.
What happens if I enter an invalid value?
You will see a clear message explaining what to correct.
Does the calculation run in my browser?
Yes. The calculator runs with JavaScript on your device.
Related tools
Last updated: October 17, 2026