Find the mean, variance, and standard deviation of a dataset, sample or population.
Your numbers — comma- or line-separated. At least 2 values for a sample.
Choose "sample" when data is a subset of a larger group; "population" when it is the whole group.
Mean
30.00
Arithmetic average of your values.
Standard Deviation
15.8114
Typical distance from the mean — the core spread measure.
Variance
250.0000
Squared spread; SD is its square root.
Count
5
Count — Calculated outcome. Derived from your inputs via the displayed formula; use to plan.
What this means
The sample formula divides by N − 1 (Bessel’s correction) to avoid underestimating the spread of the true population, while the population formula divides by N.
Standard deviation measures how spread out your data is around the mean. Choose whether your list is a full population or a sample of a larger group.
Formula
sd = √(Σ(xᵢ − mean)² ÷ N) [population] | sd = √(Σ(xᵢ − mean)² ÷ (N − 1)) [sample]
Worked examples
FAQ
Sample or population — which do I pick?
Use population when your list includes every member of the group. Use sample when it is a subset, like a quality test from a production run.
How many values do I need?
At least two are required for a sample; a population needs at least one.
Important assumptions
Pick population only when you have the entire group. Otherwise pick sample — it slightly inflates SD to avoid underestimating true variability.