Standard Deviation Calculator

Your details

Separate values with commas, spaces, semicolons or line breaks. Negatives and decimals are fine.
Choose population when your data covers the whole group; choose sample when it is a subset of a larger population.
The z* multiplier used to compute the margin of error around the mean.
Population std dev (σ)
2
Sample std dev (s)2.1381
Mean5
Median4.5
Mode4
Count (N)8
Sum40
Minimum2
Maximum9
Range7
Population variance (σ²)4
Sample variance (s²)4.5714
Sum of squares (SS)32
Coeff. of variation (CV)0.4%
Margin of error1.4816
Population variance4
Sum of squares32
Range7

Population σ = 2, mean = 5. The margin of error around the mean is +/-1.4816.

  • Standard deviation measures spread: roughly how far the values sit from the mean on average.
  • Use population σ (divide by N) when you have every member of the group; use sample s (divide by N-1, Bessel's correction) when your data is a sample drawn from a larger population. The coefficient of variation is 40.0%, indicating high relative spread.
  • In a normal distribution, about 68% of values fall within 1 SD of the mean (3 to 7), 95% within 2 SD, and 99.7% within 3 SD.

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