BESTUTILS

Sample Size Calculator

Calculate required sample size for surveys, research studies, and statistical analysis

Leave blank for infinite population

Quick Settings

Typical Sample Sizes

Small survey: 100-300
Medium survey: 300-1,000
Large survey: 1,000+
Academic research: 30-500

About the Sample Size Calculator

Our sample size calculator helps researchers, marketers, and analysts determine the optimal number of participants needed for surveys, studies, and statistical analysis. Get accurate sample size calculations based on your population size, desired confidence level, and margin of error.

Key Features:

  • Calculate sample size for finite and infinite populations
  • Multiple confidence levels (90%, 95%, 99%)
  • Customizable margin of error and expected proportion
  • Quick preset configurations for common scenarios
  • Real-time calculations with detailed explanations
  • Mobile-friendly responsive design

Statistical Formula:

Our calculator uses the standard statistical formula for sample size determination:

n = (Z² × p × (1-p)) / E²
Where: Z = Z-score, p = expected proportion, E = margin of error

How to Use the Sample Size Calculator

Step-by-Step Instructions:

  1. Enter Population Size: Total number of people in your target group (leave blank for infinite population)
  2. Select Confidence Level: Choose how confident you want to be in your results (95% is standard)
  3. Set Margin of Error: Acceptable range of sampling error (typically 3-5%)
  4. Expected Proportion: Estimated percentage of responses (use 50% if unknown for maximum sample size)
  5. Click Calculate: Get your required sample size instantly

Understanding the Parameters:

Confidence Level:
  • 90% - Less stringent, smaller sample needed
  • 95% - Standard for most research
  • 99% - Very stringent, larger sample needed
Margin of Error:

Lower percentage = more precise results but larger sample needed

Expected Proportion:

50% gives the maximum sample size (most conservative estimate)

Sample Size Tips:

For Surveys:

  • • Use 95% confidence level
  • • 3-5% margin of error is typical
  • • Consider response rates (30-50% typical)

For Research:

  • • Consider statistical power analysis
  • • Account for potential dropouts
  • • Check institutional requirements

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