Statistics tools

Distribution probabilities, hypothesis tests, confidence intervals and data summaries.

Most popular

Binomial Distribution Calculator

Probabilities of k successes in n independent trials.

Chi-Square Test of Independence

Test association between two categorical variables from a contingency table.

Combinations & Permutations Calculator

nCr and nPr, with and without repetition.

Confidence Interval Calculator

CIs for a mean (z or t) and for a proportion (Wald & Wilson).

Correlation & Linear Regression Calculator

Pearson r, Spearman ρ, R² and the least-squares line.

Descriptive Statistics Calculator

Mean, median, quartiles, variance, skewness, outliers and more.

Kaplan–Meier Survival Calculator

Survival curve, life table and median survival from time-to-event data with censoring.

Normal Distribution Calculator

Probabilities, z-scores and inverse lookups for a normal distribution.

One-Way ANOVA Calculator

Compare the means of three or more groups with an F-test.

Outlier Detector

Grubbs' test, Tukey fences and z-scores on your data.

P-value Calculator

Convert z, t, χ² or F statistics into p-values.

Poisson Distribution Calculator

PMF, CDF and tail probabilities for a Poisson distribution.

Sample Size Calculator

Required n to estimate a mean or proportion within a margin of error.

Time Series Lab: Decomposition, ETS & ARIMA Forecast

Paste a CSV: seasonal decomposition, ETS and ARIMA fits, forecast intervals and rolling-origin cross-validation.

Z-Score Calculator

Convert between values, z-scores, percentiles and areas.

t-Test Calculator

One-sample, two-sample (pooled/Welch) and paired t-tests from raw data.

Hypothesis Tests

Chi-Square Test of Independence

Test association between two categorical variables from a contingency table.

One-Way ANOVA Calculator

Compare the means of three or more groups with an F-test.

P-value Calculator

Convert z, t, χ² or F statistics into p-values.

t-Test Calculator

One-sample, two-sample (pooled/Welch) and paired t-tests from raw data.

A/B Test Significance Calculator

Two-proportion z-test with p-values, uplift and CI of the difference.

Chi-Square Goodness-of-Fit Test

Test whether observed counts match an expected distribution.

Fisher's Exact Test

Exact test for association in a 2×2 table — reliable for small counts.

Kruskal-Wallis H Test

Nonparametric comparison of three or more groups.

Mann-Whitney U Test

Nonparametric comparison of two independent samples.

Normality Test Battery

Shapiro–Wilk, D'Agostino and Kolmogorov–Smirnov in one shot.

One-Proportion Z-Test

Test a sample proportion against a hypothesised value.

Wilcoxon Signed-Rank Test

Nonparametric test for paired samples.

Levene's Test for Equal Variances

Check the equal-variance assumption before a t-test or ANOVA.

McNemar's Test

Paired 2×2 test for before/after or matched binary outcomes.

Distributions & Probabilities

Binomial Distribution Calculator

Probabilities of k successes in n independent trials.

Normal Distribution Calculator

Probabilities, z-scores and inverse lookups for a normal distribution.

Poisson Distribution Calculator

PMF, CDF and tail probabilities for a Poisson distribution.

Z-Score Calculator

Convert between values, z-scores, percentiles and areas.

Chi-Square Distribution Calculator

p-values and critical values for the χ² distribution.

Empirical Rule (68-95-99.7) Calculator

Data ranges covered by 1, 2 and 3 standard deviations.

Exponential Distribution Calculator

Waiting-time probabilities for a Poisson process.

F Distribution Calculator

p-values and critical values for the F distribution.

Geometric Distribution Calculator

Probability that the first success occurs on trial k.

Student's t Distribution Calculator

p-values and critical values for the t distribution.

Uniform Distribution Calculator

Probabilities and quantiles for a continuous uniform distribution.

Beta Distribution Calculator

Probabilities for proportions and Bayesian priors on [0, 1].

Gamma Distribution Calculator

Probabilities for waiting times and positive skewed quantities.

Hypergeometric Distribution Calculator

Sampling without replacement: successes in n draws.

Log-Normal Distribution Calculator

Probabilities for right-skewed data like incomes or file sizes.

Negative Binomial Distribution Calculator

Probability of k failures before the r-th success.

Weibull Distribution Calculator

Reliability and failure-time probabilities.

Descriptive & Data

Descriptive Statistics Calculator

Mean, median, quartiles, variance, skewness, outliers and more.

Kaplan–Meier Survival Calculator

Survival curve, life table and median survival from time-to-event data with censoring.

Outlier Detector

Grubbs' test, Tukey fences and z-scores on your data.

Time Series Lab: Decomposition, ETS & ARIMA Forecast

Paste a CSV: seasonal decomposition, ETS and ARIMA fits, forecast intervals and rolling-origin cross-validation.

Autocorrelation Calculator

ACF by lag with white-noise bands and the Ljung–Box test.

Covariance Calculator

Sample and population covariance with Pearson correlation.

Percentile Calculator

Find the value at a percentile, or the rank of a value.

Benford's Law Checker

Test whether first digits follow Benford's law — a fraud-detection classic.

GRIM & GRIMMER Test

Check whether a reported mean and SD are arithmetically possible.

Shannon Entropy & Diversity Calculator

Entropy, evenness and Simpson diversity from category counts.

Intervals, Power & Effect Size

Confidence Interval Calculator

CIs for a mean (z or t) and for a proportion (Wald & Wilson).

Sample Size Calculator

Required n to estimate a mean or proportion within a margin of error.

Cohen's d Effect Size Calculator

Effect size from group means and SDs, or from a t statistic.

Power & Sample Size for t-Tests

Required n for a target power, or the power of a given design.

Effect Size Converter

Convert between Cohen's d, r, η² and odds ratios.

Regression & Model Metrics

Correlation & Linear Regression Calculator

Pearson r, Spearman ρ, R² and the least-squares line.

Confusion Matrix Metrics Calculator

Accuracy, precision, recall, F1, MCC and more from TP/FP/FN/TN.

Polynomial Regression Calculator

Fit a polynomial of degree 2–8 with R² and residuals.

Regression Metrics Calculator

MSE, RMSE, MAE, MAPE and R² from actual vs. predicted values.

Probability & Games

Combinations & Permutations Calculator

nCr and nPr, with and without repetition.

Bayes' Theorem Calculator

Posterior probabilities, plus a diagnostic-test mode (PPV, NPV, LRs).

Dice Probability Calculator

Exact sum probabilities for any number of dice.

Expected Value Calculator

E[X], variance and SD of a discrete distribution.

Probability Calculator

Combine independent events, conditional and at-least-once probabilities.

Queueing Theory Calculator (M/M/1, M/M/c)

Waiting times, queue lengths and utilization from arrival and service rates.

Birthday Paradox Calculator

Probability that two people in a group share a birthday.

Reliability & Agreement

Cohen's Kappa Calculator

Inter-rater agreement corrected for chance.

Cronbach's Alpha Calculator

Internal consistency of a questionnaire or scale.

About these tools

Statistics calculators for students, researchers and analysts: descriptive statistics, probability distributions, confidence intervals, hypothesis tests, correlation and regression, sample size planning and power analysis. Results include the test statistics and assumptions, so they can be checked and cited with confidence.