Standard Deviation Calculator
Find the standard deviation of a data set.
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About the Standard Deviation Calculator
Standard deviation measures how spread out a data set is. Paste your numbers (separated by commas, spaces, or new lines) and the calculator returns the sample standard deviation (÷ n−1), the population standard deviation (÷ n), the variance, and the mean. It's a core statistics tool for understanding variability in test scores, measurements, and any data.
How to use the Standard Deviation Calculator
- 01Enter your list of numbers.
- 02Read the result instantly — it recalculates as you type.
- 03Adjust the numbers to model different scenarios.
Frequently asked questions
Sample vs population standard deviation?
Use sample (divide by n−1) when your data is a sample of a larger group; use population (divide by n) when it's the entire group. This tool shows both.
What does standard deviation tell me?
How far, on average, values fall from the mean. A small SD means data is tightly clustered; a large one means it's spread out.