Standard Deviation Calculator: The Complete Guide
Measure how spread out your data is. Paste or type your numbers and choose sample or population to get the standard deviation, along with the variance, mean, and count.
Who the Standard Deviation Calculator is for
Students and analysts measuring the spread or volatility of a data set.
How to use the Standard Deviation Calculator
- Type your values into the fields above — pick your currency or units where the calculator offers them.
- Results update automatically as you type; there's no submit button and nothing is sent to a server.
- Adjust any input to compare scenarios, then copy the result with a single click.
How it works
Standard deviation = √(Σ(value − mean)² ÷ n). For a sample, divide by n − 1 (Bessel's correction) instead of n. Variance is the standard deviation squared.
Features
- Sample & population
- Variance and mean
- Bessel's correction
- Instant result
Sample vs. population
Standard deviation measures how far values typically fall from the mean — low means tightly clustered, high means spread out. Use the population formula when your data is the whole group, and the sample formula (dividing by n − 1) when it's a sample used to estimate a larger population.