Standard Deviation Calculator

Sample standard deviation (s) uses n-1 in the denominator and is used when analyzing a subset of a larger population. Population standard deviation (σ) uses n and is used when you have data for the entire population. For most real-world applications, use sample standard deviation.

Use standard deviation to measure data spread in quality control, finance (volatility), scientific research (measurement precision), and academic performance analysis. It's particularly useful when you need to understand how much variation exists in your data.

A high standard deviation indicates that data points are spread out over a wider range of values, meaning there's more variability. A low standard deviation means data points are clustered close to the mean, indicating less variability.

Standard deviation is the square root of variance (SD = √variance). Both measure data spread, but standard deviation is in the same units as your original data, making it easier to interpret.

No, standard deviation is always zero or positive. It represents the average distance from the mean, so negative values don't make sense. A standard deviation of zero means all values are identical.