Standard Deviation Calculator
Paste a dataset to measure its spread around the mean and compare sample versus population formulas.
Count8
Mean19.125
Median18.5
Population SD4.567206
Sample SD4.882549
Population variance20.859375
Sample variance23.839286
How this tool works
Population variance divides squared deviations by N; sample variance divides by N−1. Standard deviation is the square root of variance.
Example
For repeated measurements, paste the observations and compare the sample standard deviation with the mean.
Common questions
Should I use sample or population standard deviation?
Use population SD when the values are the entire population of interest; use sample SD when the data are a sample used to estimate a broader population.
Why does sample variance divide by n−1?
Bessel’s correction compensates for estimating the population mean from the same sample and makes the variance estimator unbiased under standard assumptions.