Sample Size for One-Sample Proportion Test

Work out the sample size or power for testing a single binomial proportion against a hypothesized value. Enter your null and expected proportions, choose normal or exact methods, and set alpha and power targets to size the study confidently.

When to use

• Checking whether a pass rate meets a required threshold
• Validating conversion rates against a benchmark
• Designing prevalence studies with a single proportion

Inputs needed

• Null proportion (p0) and expected proportion (p1)
• Choice of exact or normal approximation
• Alpha level, target power, and test sidedness