Free Statistics Calculators
Free online statistics tools that run entirely in your browser — nothing is uploaded, nothing is stored. Each is built on the same numerical engine we use in client work and unit-tested against R. Pick a calculator below.
Describe your data
Summarise & explore
### Descriptive statistics Mean, SD, median, quartiles, IQR, range and more from pasted data.
### Correlation Pearson r, r², significance and a scatter plot from paired data.
### Z-score / normal Value ↔︎ z-score ↔︎ percentile ↔︎ probability for the normal distribution.
### Binomial probability P(X = k), P(X ≤ k) and P(X ≥ k) for n trials with success probability p.
Run a test
Hypothesis tests
### t-test One-sample, two-sample (Welch) or paired t-test from raw data.
### Chi-square test Test of independence from a contingency table, with expected counts.
### One-way ANOVA Compare 3+ groups: full ANOVA table, F, p and η².
### p-value Convert a t, z or chi-square statistic into a p-value.
### Fisher’s exact test Exact 2×2 test for small samples — p-value and odds ratio.
### Linear regression Slope, intercept, R², equation and a fitted-line plot from paired data.
Effect size & planning
Effect size, intervals & power
### Cohen’s d effect size Standardized effect size + Hedges’ g and a confidence interval.
### Confidence interval Intervals for a mean or a proportion (Wald and Wilson).
### Sample size & power Participants needed for t-tests, proportions and correlations.
Clinical & decision
Clinical + which test?
### Diagnostic test accuracy Sensitivity, specificity, PPV, NPV and likelihood ratios with 95% CIs.
### Which statistical test should I use? Answer a few questions, get the right test — and the R function.
Risk & agreement
Epidemiology & reliability
### Odds ratio, relative risk & NNT From a 2×2 table: OR, RR, absolute & relative risk reduction and NNT, each with a 95% CI.
### Cohen’s kappa Inter-rater agreement beyond chance, with a 95% CI and Landis-Koch interpretation.
Write & format