How to Calculate Standard Deviation

Standard deviation measures spread around the mean. Low SD means data clusters tightly; high SD means wide dispersion.

Step-by-step

1. Calculate the mean (x̄) of the data set.
2. Subtract the mean from each value to get deviations.
3. Square each deviation.
4. Sum the squared deviations.
5. Divide by n (population) or n−1 (sample) for variance.
6. Take the square root for standard deviation. Use our Standard Deviation Calculator to verify.

Open the Standard Deviation Calculator to apply these steps with your own numbers instantly.

Frequently asked questions