Standard Deviation & Statistics Calculator

Free standard deviation calculator. Enter a dataset to get mean, median, mode, variance, standard deviation, and other key statistics instantly. Use our free ca

Calculate ↓
Count (n) hesaplanacak
Mean (Average) hesaplanacak
Population Std Dev (σ) hesaplanacak
Sample Std Dev (s) hesaplanacak
Variance hesaplanacak
Min – Max hesaplanacak

What Is Standard Deviation?

Standard deviation (SD) measures how spread out values in a dataset are around the mean. A low SD means values cluster closely around the average; a high SD means values are more spread out. It is one of the most important measures in statistics, science, finance, and quality control.

Population vs Sample Standard Deviation

  • Population SD (sigma): Divide by N. Use when you have data for the entire population.
  • Sample SD (s): Divide by N-1. Use when your data is a sample from a larger population. This correction (Bessel's correction) reduces bias.

Calculation Steps

  1. Find the mean: sum all values divided by count
  2. Subtract the mean from each value, then square the result
  3. Find the average of those squared differences (variance)
  4. Take the square root of the variance to get standard deviation

Example

Dataset: 2, 4, 4, 4, 5, 5, 7, 9

  • Mean: 5.0
  • Variance: 4.0
  • Standard deviation: 2.0

Interpreting Standard Deviation

For a normal distribution (bell curve), approximately:

  • 68% of data falls within 1 SD of the mean
  • 95% within 2 SDs
  • 99.7% within 3 SDs

How to Use This Calculator

Using our calculator is simple: enter the required values into the input fields and click the calculate button. Results are displayed instantly on screen. You can adjust the values and recalculate to compare different scenarios and find the best option for your situation.

Frequently Asked Questions

QuestionAnswer
How accurate are the results?We use standard formulas and up-to-date 2025 rates. Individual circumstances may vary slightly.
Is this calculator free?Yes, completely free and no registration required.
What should I do for exact figures?For precise information, consult a relevant professional or official authority.
Does it work on mobile devices?Yes, it works seamlessly on all devices and screen sizes.

Important Notes

This calculator is provided for informational purposes only. For legal, financial, or medical decisions, always seek advice from qualified professionals. Calculation results do not constitute official documents. Legislative changes may affect results; please visit the relevant official website for the most up-to-date information. Our calculators are regularly updated to reflect current regulations and rates.

Related Calculators

Check out our other related calculators on the homepage for similar financial and practical calculations. Using multiple tools together helps you make better-informed decisions. Browse our category pages to discover all available calculators organized by topic.

Related Calculators

Frequently Asked Questions

Use population SD (σ) when you have data for the entire population. Use sample SD (s) when your data is a sample of a larger population — which is most common.
In a normal distribution, about 68% of values fall within 1 SD of the mean, 95% within 2 SDs, and 99.7% within 3 SDs (the empirical rule).
Variance is the average of the squared differences from the mean. Standard deviation is the square root of variance, which brings it back to the original units.