Sample and population standard deviation
The sample standard deviation divides by n - 1 and is commonly used when the dataset is a sample from a larger population. Population standard deviation divides by n and is used when the dataset contains the whole population being described.
Example
For 4, 8, 6, 5, 3, 9 and 7, the count is 7, the sum is 42 and the mean is 6. The median is also 6 after sorting the values.
Common mistakes
Check whether your data is a sample or the full population before using standard deviation. Remove labels, units and missing-value codes before pasting data.
Limitations
This calculator ignores text tokens that cannot be parsed as numbers, but it does not infer missing values, outliers or data quality problems.
Last reviewed: 2026-05-17