Free statistics calculators
Free statistics calculators
Fourteen calculators, free and without sign-up. Each one shows its working, gives you a sentence you can paste into a write-up, and says plainly what it cannot tell you.
Yes. All fourteen ResearchBench calculators are free, require no sign-up or account, and run entirely in your browser — no data is sent to a server. Each returns the result, the relevant effect size or interval where applicable, and a sentence formatted for reporting.
Chooser
Design
Sample size calculator
A priori sample size with attrition-adjusted targets and the justification sentence for your ethics form.
DesignStatistical power calculator
The power of your design, and an honest reading of what a null result would mean.
Comparison
T-test calculator
Welch's and Student's t, exact p-values, Cohen's d with a confidence interval.
ComparisonMann-Whitney U calculator
Tie-corrected U and z, p-value and effect size r — the non-parametric two-group test.
Categorical
Chi-square calculator
Goodness of fit and independence, with expected counts checked and Cramér's V.
CategoricalOdds ratio & relative risk
Odds ratio and risk ratio with 95% intervals, absolute risk reduction and NNT.
Diagnostic
Reporting
Effect size calculator
Cohen's d and Hedges' g with confidence intervals, plus conversion to r and an odds ratio.
ReportingConfidence interval calculator
t-based intervals for means and Wilson intervals for proportions.
ReportingP-value calculator
Exact p-values from t, z or chi-square statistics, one- or two-tailed.
ReportingZ-score calculator
Standardised scores with percentiles and tail proportions.
ReportingAPA results generator
Correctly formatted APA 7 reporting for eight different tests.
Evidence synthesis
Every calculation here is performed in your browser. Nothing you type is transmitted, stored or logged. The distribution functions have been verified against SciPy to twelve decimal places.
Send the data. Get a fixed quote.
Attach your dataset or just describe the project. A named statistician replies with a price and a deadline, usually within one working day.