Standard deviation and variance calculator
The standard deviation tells you if numbers sit close to the average or are spread out. Paste your numbers and pick sample or population.
Result
2Standard deviation
- Variance
- 4
- Average
- 5
- How many values
- 8
- Smallest
- 2
- Largest
- 9
- Standard deviation if it were a sample (÷ (n − 1))
- 2.13809
Inputs
- Your numbers
- 2; 4; 4; 4; 5; 5; 7; 9
- Your data is
- The whole population (n)
How it is calculated
Average m = sum ÷ n.
Result
Standard deviation
- Variance
- 4
- Average
- 5
- How many values
- 8
How it is calculated
- Average m = sum ÷ n.
- Variance = Σ(x − m)² ÷ n for a population, ÷ (n − 1) for a sample.
- Standard deviation = square root of the variance.
- The sum is built step by step (Welford’s method) to stay accurate even with large numbers.
Example
2, 4, 4, 4, 5, 5, 7, 9: average 5, population variance 4, standard deviation 2.
Good to know
- Choose “sample” if your numbers are only part of a bigger group (the most common case).
- A sample needs at least 2 values.
Frequently asked questions
What is this tool used for?
The standard deviation tells you if numbers sit close to the average or are spread out. Paste your numbers and pick sample or population.
How is the result calculated?
Average m = sum ÷ n.
What should I check before using the result?
Choose “sample” if your numbers are only part of a bigger group (the most common case).