About the standard deviation calculator
Standard deviation tells you how far values typically fall from the mean. A small value means the data is tightly clustered; a large one means it’s spread out. Choose sample when your numbers are a subset of a larger group, and population when you have every value.
How to use this calculator
- Paste or type your numbers.
- Choose sample or population.
- Read the standard deviation, variance, and mean.
Worked examples
- Mean = 40 ÷ 8 = 5
- Squared deviations sum to 32
- Population: √(32 ÷ 8) = 2
- Sample: √(32 ÷ 7) ≈ 2.138
σ = 2, s ≈ 2.138.
Measurement guidance
Which one should I use?
Survey results, test samples, and measurements from part of a group are samples. Use population only when your list includes every member of the group.
Frequently asked questions
What’s the difference between variance and standard deviation?
Variance is the average squared distance from the mean; standard deviation is its square root, in the same units as the data.
What is the coefficient of variation?
Standard deviation divided by the mean, as a percentage. It lets you compare spread between data sets with different scales.