Standard Deviation Calculator

Calculate standard deviation for any data set. Free online standard deviation calculator with variance and mean.

The Standard Deviation Calculator measures how spread out numbers are from their average. This fundamental statistical measure is essential for quality control, research, finance, and data analysis. Our calculator computes both population and sample standard deviation, variance, and mean, providing comprehensive statistical insight into your data's variability.

Common use cases

  • Quality control in manufacturing
  • Investment risk assessment
  • Scientific research analysis
  • Test score distribution analysis
  • Process capability studies

How to use

  1. Enter your numbers separated by commas
  2. Choose population or sample calculation
  3. Click calculate for standard deviation
  4. View variance, mean, and deviation
  5. Interpret the spread of your data

FAQ

What's the difference between population and sample standard deviation?

Population uses N in the denominator; sample uses N-1 (Bessel's correction) for unbiased estimation from a sample.

What does a high standard deviation mean?

High standard deviation indicates data is spread out from the mean; low indicates data is clustered near the mean.

How is standard deviation related to variance?

Standard deviation is the square root of variance, expressing spread in the same units as the original data.

What's a 'good' standard deviation?

Context-dependent. Compare to your mean using coefficient of variation (SD/mean × 100) for relative measure.