Free sample size, power, and clinical trial design calculators — t-tests, proportions, survival analysis, confidence intervals, Simon two-stage, and BOIN. Everything runs in your browser: no signup, no software, no data ever leaves your device.
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Test independence in 2×2 or general contingency tables with Pearson chi-square and Fisher exact p-values
Calculate sample size or power for comparing means between two groups
Sample size and power calculator using Pearson Chi-Square Test
Sample size and power calculator for paired designs using t-distribution
Sample size and power for time-to-event endpoints using the log-rank test
Sample size and power for non-inferiority or equivalence (TOST) trials, for means or proportions
Sample size and power for comparing 3 or more group means
Sample size and power for paired binary outcomes (before/after, or two raters)
Two-arm trial sample size with ICC, unequal cluster sizes, and attrition
Compare proportion in one sample against a null hypothesis using Binomial Test
Compare mean in one sample against a null hypothesis using One Sample T-Test
Calculate confidence intervals for proportional data
Sample size and power for testing a ROC curve's AUC against a reference value
Precision-based sample size for sensitivity and specificity with prevalence
Sample size, power, and confidence intervals for a Pearson correlation
Design and analyze two-stage clinical trials
Bayesian Optimal Interval Design for dose-finding studies
O'Brien-Fleming and Pocock stopping boundaries for interim analyses
Find optimal cutoff points in prediction of binary outcomes with bootstrap confidence intervals
Calculate the standard deviation of the ratio between two random variables
Sample size for estimating an intraclass correlation with desired precision