What is Standard Deviation?
Standard deviation is a statistical measurement that looks at how spread out a group of numbers is from the mean (average). A low standard deviation means that most of the numbers are very close to the average. A high standard deviation means that the numbers are spread out over a wider range.
Our Online Standard Deviation Calculator instantly computes the most critical statistical metrics for your dataset, supporting both Population and Sample mathematical formulas.
Sample vs. Population
It's critical to know whether your data represents an entire population or just a sample.
- Population Standard Deviation (σ): Use this when your dataset includes every member of the group you want to study (e.g., the exact grades of every student in a specific class). It divides by
N. - Sample Standard Deviation (s): Use this when your data represents only a sample or a portion of the larger population (e.g., surveying 100 people out of a city of 50,000). It uses Bessel's correction and divides by
N - 1to yield an unbiased estimator.
Metrics Computed
- Sample & Population Deviation: The primary measurement of statistical dispersion.
- Variance: The average of the squared differences from the Mean.
- Mean (Average): The central value of your dataset.
- Count (N): The total number of valid data points entered.
- Sum: The cumulative total of your dataset.