Statistics

Averages, spread, quartiles, percentiles and outliers.

• Coefficient of Variation Calculator The standard deviation as a percentage of the mean, for comparing spread between data sets.
• Geometric and Harmonic Mean Calculator The geometric and harmonic means of a list of positive numbers, beside the ordinary mean.
• Mean Absolute Deviation Calculator The average distance of values from their mean, and from their median.
• Mean, Median, Mode and Range Calculator The mean, median, mode, range and midrange of a list of numbers.
• Outlier Calculator Flags unusual values with Tukey’s fences and z-scores.
• Percentile Calculator The value at any percentile of a list of numbers, by the method you choose.
• Percentile Rank Calculator Where a value stands within a list of numbers, as a percentile rank.
• Quartile, IQR and Five-Number Summary Calculator Quartiles, the interquartile range and the five-number summary, with the method stated and compared.
• Standard Deviation and Variance Calculator Sample and population standard deviation and variance of a list of numbers.
• Weighted Average Calculator An average where some values count for more than others.

Z-scores, confidence intervals, sample size, t-tests and chi-square.

• Chi-Square Goodness of Fit Calculator Tests whether observed counts match the expected proportions.
• Chi-Square Test of Independence Calculator A chi-square test on a table of counts, with the expected counts and effect size.
• Cohen’s d Calculator The effect size between two groups, as Cohen’s d and Hedges’ g.
• Confidence Interval Calculator A confidence interval for a mean, from the sample mean, standard deviation and size.
• Confidence Interval for a Proportion Calculator A confidence interval for a percentage, by the Wilson and the simple normal (Wald) methods.
• Margin of Error Calculator The margin of error of a survey result from its sample size and confidence level.
• One-Way ANOVA Calculator A one-way analysis of variance across up to six groups, from your raw data.
• P-Value Calculator The p-value from a z, t, chi-square or F statistic.
• Proportion Z-Test Calculator A z-test for one proportion against a value, or for the difference between two proportions.
• Sample Size Calculator How many responses a survey needs for a given margin of error and confidence level.
• Sample Size for a Mean Calculator How many measurements are needed to estimate an average to a chosen precision.
• Standard Error Calculator The standard error of a mean or of a proportion.
• Statistical Power Calculator The power of a two-group t-test, and the group size needed to reach a target power.
• T-Score and Critical Value Calculator Student’s t statistic from a sample, with the critical t value for your confidence level.
• T-Test Calculator One-sample, paired and two-sample t-tests from your raw data.
• Two-Sample T-Test from Means and Standard Deviations A two-sample t-test when you only have the means, standard deviations and group sizes.
• Z-Score Calculator How many standard deviations a value is from the mean, and the share of a normal distribution below it.
• Z-Test Calculator A one-sample z-test for a mean when the population’s standard deviation is known.

Normal, binomial, Poisson, exponential and geometric.

• Binomial Distribution Calculator The chance of a given number of successes in a fixed number of independent trials.
• Exponential Distribution Calculator The chance of waiting less or more than a given time for the next event.
• Geometric Distribution Calculator The chance that the first success comes on a given trial.
• Normal Distribution Calculator Areas under a normal curve, and the value at any percentile.
• Poisson Distribution Calculator The chance of a given number of events in an interval, from the average rate.
• Uniform Distribution Calculator Probabilities, mean and variance for a continuous uniform distribution.

Probability, Bayes, combinations, dice, cards and odds.

• Bayes’ Theorem Calculator Updates a probability when new evidence comes in.
• Birthday Paradox Calculator The chance that two people in a group share a birthday.
• Card Probability Calculator The chance of drawing a number of chosen cards from a deck, without putting them back.
• Coin Flip Probability Calculator The chance of a given number of heads, and of a streak of heads, in a series of flips.
• Combination and Binomial Coefficient Calculator (nCr) The number of ways to choose items where order does not matter, including very large results.
• Conditional Probability Calculator The chance of A given B, from the probability of both and of each event.
• Dice Probability Calculator The chance of rolling a given total with any number of dice.
• Expected Value Calculator The probability-weighted average of a set of outcomes, with its variance.
• Factorial Calculator Factorials of whole numbers, including those far too large for ordinary arithmetic.
• Lottery Odds Calculator The odds of matching a lottery draw, from the numbers in play.
• Odds and Probability Calculator Converts odds to a probability, and a probability to odds.
• Odds Ratio Calculator The odds ratio from a 2×2 table of counts, with a confidence interval.
• Permutation Calculator (nPr) The number of ways to arrange items where order matters, including very large results.
• Probability Calculator The probability of an event, its complement, and the chance of it happening over repeated tries.
• Probability of Two Events Calculator The chance of A and B, A or B, exactly one or neither, for independent or mutually exclusive events.
• Relative Risk and Risk Difference Calculator The relative risk and risk difference between two groups, with confidence intervals.

Covariance, correlation, linear regression and R-squared.

• Covariance Calculator The sample and population covariance of two lists of numbers.
• Linear Regression Calculator The best-fit straight line through your data, with R² and a prediction.
• Pearson Correlation Calculator The correlation coefficient r between two lists of numbers, with a p-value and confidence interval.
• R-Squared Calculator R² and adjusted R² from actual values and a model’s predictions.
• Spearman Rank Correlation Calculator Spearman’s rank correlation between two lists of numbers, with ties handled correctly.