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🎯 Sample Size Calculator: Single Proportion

Determine the required sample size for estimating a single proportion with specified precision and confidence level. Perfect for surveys, cross-sectional studies, and prevalence studies where you want to estimate the percentage of a population with a certain characteristic.

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When to use this calculator: Use this when planning a study to estimate a population proportion (e.g., disease prevalence, customer satisfaction rate, voting preference). Input your expected proportion, desired margin of error, and confidence level to get the required sample size.

📋 Enter Study Parameters

Fill in the expected proportion, margin of error, and confidence level. The calculator will compute the minimum sample size needed for your study.

If unknown, use 0.5 (50%) for maximum sample size
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Common values: 0.05 (5%), 0.03 (3%)
Only enter if population is small (< 20,000)
✅ Sample Size Results
Required Sample Size
0
participants
Expected Proportion
0%
Margin of Error
±0%
Confidence Level
95%
Z-Score
1.96
📝 Interpretation
📐 Formula Used
n = (Z² × p × (1-p)) / d² Where: n = required sample size Z = Z-score for confidence level p = expected proportion d = margin of error For finite populations, adjust using: n_adjusted = n / (1 + ((n-1) / N))