Sample Size Calculator

Calculate the required sample size for your statistical study

Calculate sample size for estimating a population proportion (e.g., survey responses, success rates)

Population Size (N) Total size of the population (leave blank or enter 0 for infinite)

Confidence Level Probability that the true value lies within the margin of error

Margin of Error Acceptable range of error

Expected Proportion Expected percentage (use 50% if unknown for maximum sample size)

Calculate sample size for estimating a population mean (e.g., average age, income, test scores)

Population Size (N) Total size of the population (leave blank or enter 0 for infinite)

Confidence Level Probability that the true value lies within the margin of error

Margin of Error Acceptable range of error in the same units as standard deviation

Standard Deviation Expected standard deviation of the population

Calculate sample size for comparing two proportions (e.g., A/B testing, clinical trials)

Proportion 1 Expected proportion in group 1

Proportion 2 Expected proportion in group 2

Confidence Level Probability of correctly detecting a difference

Statistical Power Probability of detecting a true effect

Sample Size Needed