Sample Size Calculator

Calculate required sample size for surveys and research. Supports confidence levels, margin of error, and finite population correction.

Confidence Level

Z-score: 1.960

Margin of Error (%)

Population Proportion (%)

Use 50% if unknown (most conservative)

Population Size (optional)

Required Sample Size (Infinite Population)

385

For 95% confidence with ±5% margin of error

At 95% confidence level

±1%

9,604

±2%

2,401

±3%

1,068

±4%

601

±5%

385

±10%

Confidence Level

95%

Z-Score

1.96

Margin of Error

±5%

Population Proportion

50%

Cochran's Formula: n = (Z² × p × (1-p)) / E²

Finite Population: n_adj = n / (1 + (n-1)/N)

Where: Z = Z-score, p = proportion, E = margin of error, N = population size

• Use 50% population proportion when unknown (gives maximum sample size)

• Higher confidence levels require larger samples

• Smaller margins of error require larger samples

• Finite population correction reduces sample size for small populations

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