Sample size calculator

Calculate your smaple size

Sample Size Calculator

ℹ️ About this calculator: This tool helps researchers and statisticians determine the minimum sample size needed for hypothesis testing. Enter your study parameters below to calculate the required number of participants for each group.

Study Design

Test Type Choose based on your outcome variable type

Alternative Hypothesis Two-sided tests for difference in either direction

Group Proportions

Group 1 Proportion (p₁) Expected proportion in control group (0-1)

Group 2 Proportion (p₂) Expected proportion in treatment group (0-1)

Group Means

Group 1 Mean (μ₁) Expected mean in control group

Group 2 Mean (μ₂) Expected mean in treatment group

Standard Deviation (σ) Pooled standard deviation

Statistical Parameters

Significance Level (α) Probability of Type I error (false positive)

Power (1 – β) Probability of detecting true effect

Allocation Ratio (n₂/n₁) Group 2 size relative to Group 1 (1 = equal)

📈 Your Sample Size Results

Group 1 Sample Size

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Group 2 Sample Size

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Total Sample Size

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📊 Effect Size & Critical Values

Absolute Difference: –

Cohen’s d: –

Z(α): –

Z(β): –

📊 Sample Size Calculator