Statistics & Probability calculators
Descriptive stats, hypothesis tests, regression, distributions, probability and diagnostic test metrics.
49 free tools
Most used
Bayes' Theorem CalculatorTurn a prior, a hit rate and a false-alarm rate into a posterior probabilityBox Plot MakerDraw box-and-whisker plots for up to six data sets, with outliers markedConditional Probability CalculatorFind P(A|B), P(B|A), the union and an independence check in one goConfusion Matrix CalculatorScore a classifier: accuracy, precision, recall, F1, MCC and kappaCovariance CalculatorMeasure how two variables move together, with a step-by-step tableCritical Value CalculatorGet z, t, chi-square and F critical values for any α and tailEffect Size CalculatorCohen’s d, Hedges’ g, Glass’s Δ, η² and ω² with plain-English size labelsFive Number Summary CalculatorGet the minimum, Q1, median, Q3 and maximum of any data set instantlyGeometric Mean CalculatorAverage numbers, ratios or yearly returns the multiplicative wayHistogram MakerPaste data, pick a bin rule or width, and get a histogram and frequency tableMean Absolute Deviation CalculatorMean and median absolute deviation of any data set, step by stepOdds Ratio CalculatorOdds ratio, confidence interval and p-value from a 2×2 tableR-Squared CalculatorCoefficient of determination and adjusted R² from data or predictionsStandard Error CalculatorStandard error of the mean or a proportion, with confidence intervalZ-Test CalculatorOne- and two-sample z-tests for means with p-value and decision
More statistics & probability tools
Birthday Paradox CalculatorChance that two people in a group share a birthday — and why it is so highExponential Distribution CalculatorProbabilities, percentiles, mean and median of waiting timesExponential Regression CalculatorFit exponential, logarithmic or power curves to your dataF-Test CalculatorTest whether two variances differ, with F statistic and p-valueFisher’s Exact Test CalculatorExact two-sided and one-sided p-values for any 2×2 tableFrequency Distribution CalculatorTurn raw data into a frequency table with relative and cumulative columnsGeometric Distribution CalculatorProbability that the first success arrives on trial k — exact and cumulativeHarmonic Mean CalculatorAverage rates and ratios correctly — with optional weightsHypergeometric Distribution CalculatorExact odds of drawing k successes without replacementInverse Normal Distribution CalculatorTurn a probability or percentile into a z-score and x value (invNorm)MSE, RMSE & MAE CalculatorScore a forecast or model: MSE, RMSE, MAE, MAPE and bias in one goPooled Standard Deviation CalculatorCombine group SDs into one pooled SD — from summaries or raw dataQuadratic Regression CalculatorFit a best-fit parabola y = ax² + bx + c and see how well it fitsRelative Risk CalculatorRisk ratio, risk difference and NNT with confidence intervals from a 2×2 tableRoot Mean Square CalculatorRMS (quadratic mean) of any data set, or of a sine, square or triangle waveSpearman Rank Correlation CalculatorGet Spearman's rho, the rank table and a p-value from two lists of dataStatistical Power CalculatorFind the power of your study or the sample size you need to reach 80%Stem and Leaf Plot GeneratorPaste your numbers and get a sorted stem-and-leaf plot with a keyT Distribution CalculatorStudent's t probabilities, p-values and percentiles for any degrees of freedomTwo Proportion Z-Test CalculatorTest whether two success rates really differ, with z, p-value and CIUniform Distribution CalculatorProbabilities, mean, variance and percentiles for a continuous uniform U(a, b)Cohen's Kappa CalculatorMeasure agreement between two raters beyond chance, with CI and p-valueCronbach's Alpha CalculatorCheck the internal consistency of a survey scale in secondsDiscrete Probability Distribution CalculatorExpected value, variance and standard deviation from a probability tableKruskal-Wallis Test CalculatorCompare three or more groups without assuming normal dataMann-Whitney U Test CalculatorCompare two independent groups without assuming normalityMarkov Chain CalculatorFind n-step probabilities and the long-run steady state of a Markov chainMcNemar Test CalculatorTest whether a paired yes/no proportion changed, with exact p-valuesMultiple Linear Regression CalculatorFit Y on several predictors and see every coefficient, p-value and R²Negative Binomial Distribution CalculatorFind the chance the r-th success arrives on exactly the k-th trialSampling Distribution CalculatorUse the central limit theorem to find probabilities for a sample meanSkewness & Kurtosis CalculatorMeasure the asymmetry and tail-heaviness of your data in one stepTrimmed Mean CalculatorGet a robust average by trimming or winsorizing the extreme valuesWilcoxon Signed-Rank Test CalculatorTest paired before/after data without assuming normal differences