📊 Statistics & Probability Calculators
Descriptive stats, distributions, confidence intervals and tests. Browse 74 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.Exponential Distribution CalculatorFind the probability a waiting time is below a value, plus the mean and median of an exponential distribution.Uniform Distribution CalculatorFind the probability a value falls in an interval for a uniform distribution between two bounds.Skewness CalculatorMeasure how asymmetric a data set is from its values.Excess Kurtosis CalculatorMeasure how heavy the tails of a data set are compared with a normal distribution.Median Absolute Deviation CalculatorFind a robust measure of spread that is not pulled by outliers.Trimmed Mean CalculatorFind the average after removing the lowest and highest 10 percent of values.One Proportion Z-Test CalculatorTest whether a sample proportion differs from a hypothesised value.Two Proportion Z-Test CalculatorTest whether two groups have different proportions, such as conversion rates or survey results.Paired t-Statistic CalculatorFind the t statistic and degrees of freedom for paired measurements from the mean and spread of differences.Chebyshev Inequality CalculatorFind the most data that can lie more than k standard deviations from the mean, for any distribution.Empirical Rule (68-95-99.7) CalculatorFind how much of a normal distribution lies within a number of standard deviations of the mean.Lottery Odds CalculatorFind the number of possible combinations and the odds of winning a lottery draw.At Least One Success Probability CalculatorFind the chance of at least one success in several independent tries.Combined Mean of Two Groups CalculatorFind the overall mean of two groups from their sizes and means.Pooled Standard Deviation CalculatorCombine the spread of two samples into one pooled standard deviation.Percentile Rank of a Score CalculatorFind what percent of a data set falls below a given score.Normal Distribution Interval Probability CalculatorFind the probability that a normally distributed value lies between two bounds.Mean Absolute Deviation CalculatorFind the average distance of values from their mean.Gini Coefficient CalculatorMeasure inequality in a set of incomes or amounts, from 0 for perfect equality to 1 for total inequality.Number Needed to Treat CalculatorFind how many people must be treated to prevent one extra bad outcome, from the event rates in two groups.Variance of a Sum of Two Variables CalculatorFind the variance and standard deviation of the sum of two random variables, including their covariance.Expected Value of a Bet CalculatorFind the average profit or loss per bet from the chance of winning and the amounts won and lost.Kelly Criterion Bet Size CalculatorFind the fraction of your bankroll to bet to maximise long-run growth, from the win probability and payout odds.Logit and Odds CalculatorConvert a probability into odds and log-odds, as used in logistic regression.Series System Reliability CalculatorFind the reliability of a system that fails if any one of its components fails.Parallel System Reliability CalculatorFind the reliability of two redundant components where the system works if either one works.System Availability CalculatorFind the availability of a repairable system from its mean time between failures and mean time to repair.Exponential Smoothing Forecast CalculatorForecast the next value of a series by weighting the latest actual value and the previous forecast.Range Rule of Thumb Standard Deviation CalculatorEstimate the standard deviation of a data set quickly from its range.Standard Error of a Proportion CalculatorFind the standard error and 95 percent margin of error of a sample proportion.Two-Sided P-Value from Z CalculatorConvert a z statistic into a two-sided and one-sided p-value.Coupon Collector Expected Draws CalculatorEstimate how many random draws are needed to collect every one of a set of distinct items.Wilson Score Interval CalculatorFind a 95 percent confidence interval for a proportion that works well even with small samples or extreme proportions.Diagnostic Likelihood Ratio CalculatorFind how much a positive or negative test result changes the odds of disease, from sensitivity and specificity.Positive and Negative Predictive Value CalculatorFind the chance a positive or negative test result is correct, given sensitivity, specificity and disease prevalence.Binomial Mean and Standard Deviation CalculatorFind the expected number of successes and its spread for a fixed number of independent trials.
About Statistics & Probability calculators
Descriptive stats, distributions, confidence intervals and tests. CalcDepo has 74 free statistics & probability calculators. Each one shows the formula, the variables and their units, a worked example and a chart of how the result changes, so you can check homework, plan a lab or understand the idea behind the numbers.
Popular calculators here include Mean, Median and Mode, Standard Deviation, Quartiles and IQR, Percentile, Z-Score, Normal Distribution Probability. Common searches in this category include “mean median mode calculator”, “spread of data”, “box plot”, “what is the 90th percentile”.
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