Statistics

Find the percentile value of any data set using linear interpolation. Free online percentile calculator that ranks your numbers and returns the value at any chosen percentile.

Calculate population and sample standard deviation, variance and mean of any data set instantly. Free online standard deviation calculator with step-by-step results.

Calculate the z-score (standard score) of a value from its mean and standard deviation. Free online z-score calculator showing how many standard deviations a point is from the mean.

Calculate classification accuracy, precision, recall, F1 score, specificity and NPV from a confusion matrix (TP, TN, FP, FN).

Run a one-way ANOVA F-test from group summary statistics (n, mean, SD) and get the F statistic, p-value, and effect size.

Update a prior into a posterior probability using sensitivity and false-positive rate via Bayes rule.

Find binomial probabilities P(X=k), at most or at least k successes in n trials, plus mean and variance.

Probability that at least two people in a group share a birthday, for any group size and number of days.

Odds of drawing favorable cards from a deck: exactly k, or at least one, in n draws without replacement.

Test whether observed counts match expected counts or proportions with a chi-square test.

Test association between two categorical variables from a contingency table.

Compute the coefficient of variation (CV = SD/mean) as a percentage from data or summary stats.

Probability of getting k heads in n coin flips (fair or biased), exactly, at least or at most.

Find P(A given B) from the joint probability and P(B), and check whether two events are independent.

Calculate a confidence interval for a mean using the z-distribution. Free online confidence interval calculator for 90%, 95% and 99% levels showing margin of error, lower and upper bounds.

Calculate the Pearson correlation coefficient (r) between two data sets to measure the strength and direction of their linear relationship. Free online correlation calculator with r² and slope.

Compute sample or population covariance between two equal-length variables x and y.

Calculate all nine deciles (D1–D9) for any data set. Deciles divide data into ten equal parts at the 10th, 20th, … 90th percentiles.

Compute mean, median, mode, range, variance and standard deviation for any data set.

Calculate the expected value, min, max, variance, and standard deviation for any dice expression (NdS + modifier).

Probability of rolling a target sum with any number and type of dice, exactly, at least or at most.

Apply the 68-95-99.7 rule to a normal dataset: get the one, two and three sigma intervals and percentages.

Compute expected value, variance and standard deviation from a discrete probability distribution table.

Find exponential probabilities P(X<x) and P(X>x) for a given rate, plus mean and variance.

Get min, Q1, median, Q3, max and IQR from a data set for a box-plot summary.

Find the probability the first success occurs on trial k, plus cumulative probability, mean and variance.

Probability of drawing k successes in n draws without replacement from a finite population of N.

Compute the interquartile range, Tukey fences, and flag outliers in a data set.

Find the interquartile range, quartiles, and five-number summary for any data set — with a normal-distribution visualization of the IQR.

Fit a least-squares line: slope, intercept, R-squared, equation, and prediction at a value.

Calculate lottery jackpot odds and prize-tier probabilities for any pool size and draw count using combinations.

Calculate the margin of error for a mean or a proportion at a chosen confidence level.

Calculate the mean absolute deviation, mean, median, range, and standard deviation of any data set.

Find the median, Q1, Q3, interquartile range, mode and range of any dataset — enter numbers separated by commas.

Calculate the midrange of a data set — the average of the minimum and maximum values — instantly from any list of numbers.

Find the mode (most frequently occurring value) of any dataset, with frequency breakdown and support for bimodal and multimodal data.

Calculate Mean Squared Error (MSE), Root MSE (RMSE), Mean Absolute Error (MAE), and R² from actual and predicted values.

Probability of k failures before the r-th success, with cumulative options, mean and variance.

Convert z-scores to area and area to z, and find P(X<x), P(X>x), or between for any normal curve.

Convert between probability, decimal odds, fractional odds, and American/moneyline odds in one step.

Convert odds to probability and probability to odds (for and against) with a clean visual breakdown.

Test whether a sample proportion differs from a hypothesized proportion using a z-test.

Test whether a sample mean differs from a hypothesized value with a one-sample t-test.

Compare three or more group means with a one-way ANOVA F-test from data lists.

Detect outliers in a data set using the Z-score method — flag any value more than k standard deviations from the mean.

Convert a z, t, chi-square, or F test statistic into a p-value for any tail.

Test the mean difference between paired/before-after measurements with a paired t-test.

Calculate permutations (nPr) and combinations (nCr) for any n and r. Free online permutation and combination calculator using factorials, with instant results.

Compute Poisson probabilities P(X=k), at most, or at least k events given an average rate lambda.

Calculate the probability of two independent events: P(A and B), P(A or B) and the complement P(not A). Free online probability calculator for single and combined events.

Find Q1, Q2 (median), Q3, IQR and Tukey outlier fences for any data set — with a normal-distribution visualization and five-number summary.

Calculate the statistical range of a data set — the difference between the maximum and minimum values — plus mid-range and mean.

Calculate residuals (observed − predicted) for a set of data points. Get RSS, MSE, RMSE and a residual plot to diagnose model fit.

Calculate Relative Risk (RR), Odds Ratio (OR), Absolute Risk Difference and Number Needed to Treat/Harm from a 2×2 contingency table.

Calculate Relative Standard Error (RSE = SE / Mean × 100%) to assess the reliability of a survey or sample estimate.

Find the sample size needed to estimate a population mean within a target margin of error.

Compute the sample size needed to estimate a proportion within a chosen margin of error.

Calculate Simpson's Diversity Index (D) plus Shannon entropy and Pielou's evenness from species or category counts.

Find the standard error of the mean (SEM) from a data list or from sample SD and size.

Compare two independent sample proportions with a pooled two-proportion z-test.

Compare two independent group means with Welch's or pooled two-sample t-test.

Continuous uniform probability over [a,b]: find P(c<X<d), mean and variance instantly.

Compute complement, union and intersection probabilities for two events, independent or with joint given.

Calculate a weighted average (weighted mean) from value and weight pairs. Free online weighted average calculator for grades, GPAs, prices and survey data.

Calculate the mean x̄ = Σ m·p(x), variance, and standard deviation from a grouped frequency distribution using class midpoints.