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.
DesignEffective sample size calculator
Design effect and effective sample size for clustered or repeated-measures data, with the wording for your methods section.
DesignIntraclass correlation calculator
Paste grouped data and get the ICC, the variance components behind it and your effective sample size.
AnalyseMultiple comparisons calculator
Bonferroni, Holm and Benjamini-Hochberg side by side, so you can see what survives correction.
ReportSTROBE checklist
All 22 reporting items for observational studies, with outstanding items you can copy.
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
PRISMA flow diagram generator
A PRISMA 2020 diagram as a downloadable SVG, with your counts checked for consistency.
Theory of change builder
Inputs to impact, with the diagram and the narrative paragraph, downloadable as SVG.
Clinical audit sample size calculator
How many records you need, and whether a change at re-audit would be detectable.
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.