TetraKitsStandard Deviation Calculator
Calculate standard deviation and variance from any data set — population or sample. Paste comma-separated numbers and read mean, σ or s, variance, and count for statistics homework, QC, and research.
Read: Standard Deviation Calculator Guide: Sample vs Population σ →
- Free to Use
- No Signup
- Privacy Friendly
How to calculate standard deviation
- 1
Enter your data
Paste numbers separated by commas, spaces, or line breaks. Example: 12, 15, 14, 18, 16, 13.
- 2
Choose population or sample
Use sample (n−1 denominator) when data is a subset of a larger group. Use population (n denominator) for the complete data set.
- 3
Read σ, variance, and mean
See standard deviation, variance, mean, and count. For central tendency only, use the average calculator.
Standard deviation formulas
- σ, s — standard deviation (square root of variance)
- n — number of values
- Use sample (n−1) when data is a subset of a larger population
Why Use This Tool?
Both σ Types
Sample (n−1) and population (n) standard deviation side by side.
Full Stats
Mean, variance, standard deviation, and count in one view.
Easy Input
Paste comma, space, or newline-separated numbers.
Local Only
Your dataset never leaves the browser.
Frequently Asked Questions
What is the difference between sample and population standard deviation?
Population (σ) divides by n — use when you have the entire data set. Sample (s) divides by n−1 — use when data is a sample of a larger population.
How is standard deviation calculated?
SD = √(Σ(x − mean)² / n) for population, or divide by n−1 for sample. It measures spread around the mean.
What is variance?
Variance is SD squared (σ²). Standard deviation is in the same units as your data — easier to interpret.
How many data points do I need?
At least two values for sample SD. More data points produce more stable estimates.
Is this standard deviation calculator free?
Yes. Unlimited data sets with no signup.
Measure Spread Around the Mean
Quality control charts, survey analysis, and statistics coursework all need standard deviation — not just averages. Paste a data set, pick population or sample mode, and read σ, variance, and mean together.
