Sample Size Calculator
Calculate the required sample size for surveys, experiments, and research studies with statistical precision and power analysis.
Sample Size Parameters
Configure your study parameters to calculate optimal sample size
Use 50% if unknown (most conservative)
Sample Size Fundamentals
Why Sample Size Matters
Sample size determines the precision and reliability of your research findings. Too small, and your results may not be reliable. Too large, and you waste resources.
Key Concepts
Confidence Level: The probability that your sample accurately represents the population
95% means you can be 95% confident in your results
Margin of Error: The range of uncertainty around your estimate
±3% means the true value is within 3% of your estimate
Power: The probability of detecting an effect if it truly exists
80% power means 80% chance of detecting a real difference
Trade-offs
- Higher confidence level → Larger sample size needed
- Smaller margin of error → Larger sample size needed
- Higher statistical power → Larger sample size needed
- Smaller effect size → Larger sample size needed