Standard Deviation Calculator
Calculate standard deviation, variance, mean, and other statistics for a data set
Count (n)
8
Mean
18
Median
18.5
Std Dev (σ)
4.898979
Std Dev (s)
5.237229
Variance (σ²)
24
Variance (s²)
27.428571
Sum
144
Range
13
Min
10
Max
23
Frequently Asked Questions
What is standard deviation?▼
Standard deviation measures how spread out numbers are from the mean. A low SD means data points cluster near the mean; high SD means they're spread out.
Population vs sample standard deviation?▼
Population SD divides by N, sample SD divides by N-1 (Bessel's correction). Use sample SD when your data is a subset of a larger population.