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Statistics & Probability Calculators
Mean, standard deviation, confidence interval, hypothesis test, regression and probability calculators. 52 free tools that run in your browser, no sign-up needed.
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Weighted Average CalculatorCalculate a weighted mean from values and weights, step by step.Average CalculatorMean, weighted average, median, sum, min and max of any list.Standard Deviation CalculatorStandard deviation, variance, mean, median, mode and quartiles.A/B Test Significance CalculatorCheck if your A/B test result is statistically significant.Z-Score CalculatorZ-score from a value, mean and SD, plus percentile and p-value; or the value from z.Probability CalculatorFind and, or, not, conditional and at-least-once probabilities from P(A) and P(B).Permutation and Combination CalculatorCalculate nPr and nCr, with or without repetition, as exact big numbers.Mean Median Mode CalculatorFind the mean, median, mode, range, min, max, sum and count of a list of numbers.Confidence Interval CalculatorConfidence interval and margin of error for a mean or a proportion, with steps.Sample Size CalculatorHow many survey responses you need for a given confidence level and margin of error.Percentile CalculatorValue at any percentile, percentile rank of a score, quartiles, IQR and outliers.Correlation Coefficient CalculatorPearson r and Spearman rank correlation with significance and interpretation.Average Order Value CalculatorAverage order value from revenue and orders, plus the revenue impact of raising AOV.Binomial Distribution CalculatorBinomial probabilities P(X = k), at most, at least or between, with mean, variance and chart.Normal Distribution CalculatorNormal probabilities P(X < x), between two values and inverse percentiles, on a shaded bell curve.Poisson Distribution CalculatorPoisson probabilities for a rate λ: exactly k, at most, at least or between, with a chart.T-Test CalculatorOne-sample, two-sample (Welch/pooled) and paired t-tests with p-value and CI.Chi-Square CalculatorChi-square goodness-of-fit and independence tests with p-value and expected counts.P-Value CalculatorOne- or two-tailed p-values from z, t, chi-square or F statistics, with critical values.Variance CalculatorSample and population variance and standard deviation with a step-by-step deviations table.Five Number Summary CalculatorMin, Q1, median, Q3, max, IQR and fences of a data set, with a box plot.Outlier CalculatorFind outliers with 1.5×/3× IQR fences, z-scores or modified z-scores; get the cleaned data.Geometric Mean CalculatorGeometric, harmonic, arithmetic and quadratic means compared, or average growth from % changes.Expected Value CalculatorExpected value, variance and standard deviation from outcomes and their probabilities.One-Way ANOVA CalculatorOne-way ANOVA for 2-10 groups: SS, df, MS, F statistic, p-value, effect size and full table.Bayes Theorem CalculatorPosterior P(A|B) from P(A), P(B|A) and P(B|not A), with a probability tree and table.Box Plot MakerPaste data to draw box-and-whisker plots with quartiles, IQR and outliers. Download PNG or SVG.Coefficient of Variation CalculatorCV % from a dataset (sample or population) with mean, SD and a two-dataset comparison.Critical Value CalculatorCritical values of z, t, chi-square and F for any alpha, tails and degrees of freedom.Dice Probability CalculatorOdds of rolling a sum (exactly, at least, at most) with any dice, plus the full distribution.Effect Size Calculator (Cohen's d)Cohen's d, Hedges' g and Glass's delta from two means, SDs and sample sizes, with CI.Frequency Table GeneratorMake a frequency, relative and cumulative frequency table from numbers or categories.Histogram MakerPaste numbers, choose bins and get a histogram, frequency table and PNG download.Margin of Error CalculatorSurvey margin of error from sample size, confidence and proportion, with population correction.Moving Average CalculatorSimple, exponential and weighted moving averages of a data series, with table and line chart.Odds Ratio and Relative Risk CalculatorOdds ratio, relative risk, risk difference, 95% CIs and p-values from a 2x2 table.Standard Error CalculatorStandard error of the mean from data or SD and n, plus SE of a proportion, with CIs.Descriptive Statistics CalculatorPaste data and get mean, median, mode, quartiles, SD, skewness, kurtosis and a histogram.Empirical Rule Calculator68-95-99.7 rule ranges from a mean and standard deviation, with a shaded bell curve.Z-Table (Standard Normal Table)Interactive z-table: find the area for any z-score, or the z-score for a probability.Average Rate of Change CalculatorAverage rate of change of f(x), two points or a data table over [a, b], with the secant line.Binomial Expansion CalculatorExpand (a + b)^n with the binomial theorem: every term, Pascal coefficients and any specific term.Combinations GeneratorList every k-combination of your items, with or without repetition, and copy or export them.Covariance CalculatorSample and population covariance of paired X and Y data, with a step table and scatter plot.Grouped Data CalculatorMean, median, mode, variance and standard deviation from class intervals and frequencies.Inverse Normal Distribution CalculatorinvNorm: find the x or z value for a left, right, central or two-tail area, with a shaded curve.Permutations GeneratorList all permutations of letters, words or items, with k-permutations and repeats, and export them.Statistical Power CalculatorPower or required sample size for t-tests, proportions and correlations, with a power curve.T Distribution CalculatorStudent's t probabilities and critical values for any df, with the area shaded on the curve.T-Table (Student's t Distribution)Interactive t-table: critical t-values for any df and α, p-values, and a printable full table.Z-Test CalculatorOne-sample, two-sample and proportion z-tests with z, p-value, decision and shaded curve.Shannon Entropy CalculatorEntropy of text, data or probabilities in bits, nats or hartleys with a frequency table.
About Statistics & Probability Calculators
Calculate averages, standard deviation, z-scores, confidence intervals, probabilities and A/B test significance. They are useful for homework as well as quick checks on real data.
Most used here: Weighted Average Calculator, Average Calculator and Standard Deviation Calculator.