Statistics calculators for data, probability, and inference
Calculate mean, median, mode, range, variance, standard deviation, z-scores, percentiles, quartiles, confidence intervals, sample size, binomial probability, normal probability, Poisson probability, combinations, permutations, correlation, regression, chi-square, and t-tests. Each page includes formulas, examples, result details, FAQs, and structured data.
Search by calculator name, topic, data method, or probability question.
Descriptive statistics
8 calculators
Mean Calculator
Calculate arithmetic mean from a data set with sum, count, and average breakdown.
Open calculatorAverage Calculator
Find the average value of numbers and review total, count, minimum, and maximum.
Open calculatorMedian Calculator
Calculate the median middle value after sorting a numeric data set.
Open calculatorMode Calculator
Find the most frequent value or values in a data set.
Open calculatorRange Calculator
Calculate statistical range from minimum and maximum values.
Open calculatorVariance Calculator
Estimate sample variance and population variance from numeric observations.
Open calculatorStandard Deviation Calculator
Calculate sample and population standard deviation with variance details.
Open calculatorCoefficient of Variation Calculator
Calculate relative variability as standard deviation divided by mean.
Open calculatorScores and percentiles
6 calculators
Z Score Calculator
Convert a raw value into a z-score using mean and standard deviation.
Open calculatorPercentile Calculator
Estimate percentile rank from values below, equal values, and total observations.
Open calculatorQuartile Calculator
Calculate Q1, median, Q3, and quartile positions from sorted data.
Open calculatorInterquartile Range Calculator
Calculate IQR and outlier fences using first and third quartiles.
Open calculatorFive Number Summary Calculator
Find minimum, Q1, median, Q3, and maximum for a data set.
Open calculatorOutlier Calculator
Estimate lower and upper outlier fences using the IQR rule.
Open calculatorInference and surveys
6 calculators
Confidence Interval Calculator
Calculate confidence interval for a mean from sample size, standard deviation, and z value.
Open calculatorMargin of Error Calculator
Estimate survey or sample margin of error from confidence and sample size.
Open calculatorSample Size Calculator
Calculate sample size required for a proportion estimate and selected margin of error.
Open calculatorProportion Calculator
Calculate sample proportion, failure rate, and standard error from successes and trials.
Open calculatorOne Sample T Test Calculator
Calculate one-sample t statistic from mean, hypothesized mean, standard deviation, and n.
Open calculatorChi Square Calculator
Calculate chi-square statistic from observed and expected category counts.
Open calculatorProbability distributions
8 calculators
Binomial Probability Calculator
Calculate exact binomial probability for successes across independent trials.
Open calculatorNormal Distribution Calculator
Estimate normal distribution z-score, cumulative probability, and upper-tail probability.
Open calculatorPoisson Distribution Calculator
Calculate Poisson probability for event counts given an average rate.
Open calculatorProbability Calculator
Calculate event probability from favorable outcomes and total outcomes.
Open calculatorOdds Calculator
Convert favorable and total outcomes into probability and odds against.
Open calculatorPermutation Calculator
Calculate ordered arrangements using nPr for selections where order matters.
Open calculatorCombination Calculator
Calculate unordered selections using nCr where order does not matter.
Open calculatorExpected Value Calculator
Calculate expected value from outcomes and probability weights.
Open calculatorRegression and relationships
5 calculators
Correlation Calculator
Calculate Pearson correlation from paired x and y values.
Open calculatorLinear Regression Calculator
Fit a linear regression line with slope, intercept, and prediction.
Open calculatorSlope Intercept Regression Calculator
Calculate slope and intercept for paired data using least squares.
Open calculatorCovariance Calculator
Estimate covariance and relationship direction from paired x and y data.
Open calculatorR Squared Calculator
Calculate R squared from correlation to estimate explained variance.
Open calculatorApplied statistics
4 calculators
Grade Weighted Average Calculator
Estimate weighted grade average using scores and category weights.
Open calculatorData Set Summary Calculator
Summarize a numeric data set with mean, count, min, max, and spread.
Open calculatorFrequency Calculator
Find frequency counts and the most common value in a data set.
Open calculatorStatistics Calculator
Calculate common descriptive statistics including mean, variance, and standard deviation.
Open calculator