📊 Statistics & Probability Calculators
Descriptive stats, distributions, confidence intervals and tests. Browse 38 free statistics & probability calculators, each with the formula, a worked example and an interactive chart.
Mean, Median and Mode CalculatorCompute the mean, median, mode and range of a data set.Standard Deviation CalculatorCompute sample and population standard deviation and variance.Quartiles and IQR CalculatorFind Q1, Q3, interquartile range and outlier fences.Percentile CalculatorFind the value at a given percentile of a data set.Z-Score CalculatorStandardise a value and find its percentile.Normal Distribution Probability CalculatorFind the probability between two values for a normal distribution.Inverse Normal (Percentile to Value) CalculatorFind the value that matches a cumulative probability.Binomial Probability CalculatorFind the probability of k successes in n trials.Cumulative Binomial Probability CalculatorFind P(X ≤ k) for a binomial distribution.Poisson Probability CalculatorFind the probability of k events with a known average rate.Geometric Distribution CalculatorFind the probability that the first success occurs on trial k.Hypergeometric Probability CalculatorFind the probability of drawing k successes without replacement.Probability of Events CalculatorCompute probabilities of A and B, A or B, and conditional.Conditional Probability and Bayes CalculatorApply Bayes' theorem to update a probability.Expected Value CalculatorCompute expected value and variance of a discrete variable.Confidence Interval for a Mean CalculatorFind a confidence interval for a mean using the normal approximation.Confidence Interval for a Proportion CalculatorFind a confidence interval for a proportion.Sample Size CalculatorFind the sample size needed for a survey proportion.One-Sample t-Test CalculatorCompute the t statistic comparing a sample mean to a value.Two-Sample t-Test (Welch) CalculatorCompare the means of two groups.Correlation Coefficient CalculatorCompute Pearson's r for two variables.Linear Regression CalculatorFit a least-squares line and predict y.Chi-Square for a 2×2 Table CalculatorTest independence in a 2×2 contingency table.Coefficient of Variation CalculatorFind relative variability of a data set.Weighted Average (GPA) CalculatorCompute a weighted average of scores.Moving Average CalculatorCompute the simple moving average of the latest values.Geometric and Harmonic Mean CalculatorCompute geometric, harmonic and root mean square of positive numbers.Range, Midrange and Outliers CalculatorFind range, midrange and potential outliers.Standard Error CalculatorCompute the standard error of the mean.Cohen's d Effect Size CalculatorCompute the standardised difference between two means.Statistical Power Calculator (Two Means)Estimate power of a two-sample comparison.Dice Probability CalculatorFind the chance of a total on one or two dice.Birthday Problem CalculatorFind the chance two people share a birthday.Odds and Probability ConverterConvert between probability, odds and percentage.Relative Risk and Odds Ratio CalculatorCompute risk ratio and odds ratio from exposure outcomes.Margin of Error from Percent CalculatorFind the margin of error for a poll percentage.Coefficient of Determination CalculatorConvert r to R² and explained variance.Finite Population Correction CalculatorAdjust a sample size for a small population.
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🚀 Mechanics & Motion🔥 Thermodynamics & Fluids⚡ Electricity & Magnetism🌈 Waves, Sound & Optics🪐 Modern Physics & Astronomy⚗️ General Chemistry🧪 Solutions, Acids & Kinetics🧬 Genetics & Molecular Biology🌿 Ecology & Evolution🫀 Human Body & Health∑ Algebra & Calculus📐 Geometry & Trigonometry🌍 Earth & Environmental Science