Statistics

Standard deviation calculator for sample and population data. Find standard deviation, variance, mean, sum, and range from a list of numbers instantly.

Standard deviation calculator: compute sample SD, population SD, mean, variance, and CV from any dataset. Enter numbers and get results instantly.

Variance calculator for sample and population data. Computes variance, standard deviation, mean, median, mode, and IQR from any list of numbers instantly.

Calculate the pooled standard deviation for two samples using sizes, means, and standard deviations. Accurate results for t-tests and statistical analysis.

Standard deviation of sample mean (SEM) calculator: compute SEM, mean, variance, and SD from raw data. Enter comma-separated numbers to get results instantly.

Standard error calculator: compute SE from raw data or summary statistics. Includes confidence intervals at 90%, 95%, and 99% — free and accurate.

Calculate Relative Standard Deviation (RSD) and Coefficient of Variation (CV) instantly. Free statistical analysis tool for data dispersion and precision.

Relative Standard Error (RSE) calculator — divide standard error by the estimate to get a unit-free precision percentage and a qualitative reliability rating.

Weighted mean calculator for grades, finance, and surveys. Enter values and weights to compute the weighted average — supports any number of data points.

IQR calculator: compute interquartile range, Q1, Q3, and identify outliers from any dataset. Enter comma-separated numbers and get instant quartile analysis.

Outlier calculator using the IQR method: enter a data set to find mild outliers (1.5×IQR) or extreme outliers (3×IQR) with Q1, Q3, and fence values instantly.

Calculate upper and lower fences using the IQR method to identify outliers in your dataset. Instantly find Q1, Q3, IQR, and all data points outside the fences.

Coefficient of variation calculator: enter comma-separated numbers to get mean, sample standard deviation, and CV% for instant relative variability comparison.

Dispersion calculator: enter comma-separated numbers to get range, variance, standard deviation, IQR, coefficient of variation, and MAD in one click.

Calculate population variance, standard deviation, and mean for any data set. Free online statistical dispersion tool — paste numbers and get results instantly.

Find k in y = kx with this proportionality calculator. Enter one or more (x, y) pairs to compute the constant and verify direct proportion.

Calculate Cohen's d effect size from two group means, standard deviations, and sample sizes. Ideal for psychology, education, and medical research analysis.

Paired samples t-test calculator: enter two matched data groups to get the t-statistic, degrees of freedom, p-value, and 95% confidence interval.

One-sample and two-sample Z-test calculator for hypothesis testing. Enter sample mean, population SD, and sample size to get the Z-statistic and p-value.

P-value calculator for Z, T, F, and Chi-square tests: enter a test statistic and degrees of freedom to get the exact p-value and significance verdict.

Perform an F-test for equality of two variances. Enter sample variances and sizes to get the F-statistic, p-value, and reject/fail-to-reject decision.

Calculate the F-statistic and p-value for comparing two sample variances. Enter group variances and sizes to run an ANOVA or F-ratio test instantly.

Wilcoxon signed-rank test calculator for paired samples. Compare before-and-after measurements with W statistic, Z-score, and p-value — no normality assumption.

Perform a Wilcoxon Rank Sum Test (Mann-Whitney U) for two independent samples. Get the U statistic, Z-score, and p-value instantly — no normality required.

Run Fisher's Exact Test on a 2×2 contingency table. Get one-tailed and two-tailed p-values plus the odds ratio — ideal for small sample sizes in research.

Wald test calculator for statistical significance. Enter parameter estimate, standard error, and alpha level to get the Wald statistic, z-score, and p-value.

Sample size calculator using Cochran's formula. Enter confidence level, margin of error, and proportion to get the minimum sample size for reliable surveys.

Confidence interval calculator for sample means. Enter summary stats or raw data to get CI bounds, margin of error, and SE at 90%, 95%, or 99%.

Hypothesis testing calculator for Z-tests and T-tests. Compute test statistic, p-value, and critical value to determine statistical significance.

Z-score calculator: find how many standard deviations a value is from the mean. Enter raw score, mean, and standard deviation to get z-score and interpretation.

Perform one-way repeated measures ANOVA analysis. Enter subject data to get F-statistic, effect size (eta squared), and complete ANOVA table instantly.

Perform Tukey's HSD post-hoc test after ANOVA. Compare all group mean pairs to find statistically significant differences with one free online tool.

Spearman's rank correlation calculator: compute ρ for two datasets. Measures monotonic relationships without normality requirements — ideal for ordinal data.

Fit data to a polynomial equation with this free curve fitting tool. Get the best-fit polynomial equation, R-squared value, and predict new values instantly.

Fit an exponential regression model y = ab^x to your data. Get coefficients a and b, R-squared, correlation, and predicted values from paired data points.

Calculate linear regression residuals instantly. Enter X and Y values to get the regression line, predicted values, residuals, and R-squared for any dataset.

Find P(A|B), joint P(A∩B), or marginal P(B) with this conditional probability calculator. Covers Bayes' theorem and real-world probability problems.

Calculate expected value, variance, and standard deviation for discrete probability distributions. Enter outcomes and probabilities to get E[X] instantly.

Free nCr nPr calculator: enter n and r to compute combinations and permutations instantly for probability, lottery, and combinatorics.

Implied probability calculator: convert American, Decimal, or Fractional betting odds to a winning probability percentage for sports betting value analysis.

Online coin flipper: simulate one or thousands of random coin tosses, choose fair or biased coins, and track real-time heads/tails counts and percentages.

Binomial coin flip probability calculator: find the chance of N heads in any number of flips — compute exactly, at least, or at most outcomes instantly.

Coin streak probability: find the chance of consecutive heads or tails in N tosses, or compute the expected tosses needed to achieve any streak length.

Dice roller calculator: simulate rolling multiple dice and get instant statistics — mean, median, mode, standard deviation, and full frequency distribution.

Dice probability calculator: find exact, at-least, or at-most probabilities for any combination of dice with up to 10 dice and 20 sides per die.

Roulette payout calculator for American and European wheels. Enter bet type and wager to get net winnings, total payout, payout odds, and win probability.

Explore the Two Envelopes Paradox interactively. Calculate expected values for switching or keeping, and understand the probability math behind this puzzle.

Calculate the probability of truly having a condition after a positive test. Enter prevalence, sensitivity, and specificity to see the false positive paradox.

Inverse normal distribution calculator: find the x-value for a given probability. Supports left-tailed, right-tailed, and two-tailed modes with custom μ and σ.

Calculate exact and cumulative Poisson probabilities instantly. Find P(X=x), P(X≤x), P(X≥x) for any lambda and event count — free online statistics tool.

Compute exponential distribution PDF, CDF, mean, variance, and survival probability. Enter rate parameter λ and value x for instant statistical results.

Calculate PDF, CDF, mean, variance, and interval probability for any uniform distribution. Enter the range parameters a and b to get instant results.

Weibull distribution calculator for reliability analysis. Compute PDF, CDF, hazard rate, mean, median, and variance from shape and scale parameters instantly.

Rayleigh distribution calculator: compute PDF, CDF, complementary CDF, mean, median, mode, and variance from scale parameter σ and value x instantly.

Sampling distribution of the sample mean calculator: find SE, z-score, and probability (less than, greater than, between) using the Central Limit Theorem.

Sampling distribution of the sample proportion calculator. Find mean, standard error, normality check, Z-score, and cumulative probabilities instantly.

Create a frequency distribution table from any data set. Calculate frequency, relative frequency, cumulative frequency, mean, median, and standard deviation.

Dot plot calculator: enter a data set to generate a visual dot plot with mean, median, mode, and range — perfect for classrooms and quick data exploration.

Relative frequency calculator: enter a comma-separated data set and instantly get frequency counts, relative frequency, and cumulative frequency for each value.

Venn diagram calculator for 2 and 3 sets. Find union, intersection, and exclusive regions instantly — ideal for set theory, probability, and survey analysis.

Calculate AUC and plot ROC curves for binary classifiers. Input prediction scores and true labels to get sensitivity, specificity, and optimal threshold.

Calculate the Upper Control Limit (UCL) for statistical process control charts. Enter raw data or summary stats to monitor process variation and quality.

Index of Qualitative Variation calculator: measure categorical data diversity from frequency counts. Compute IQV, observed and possible pairs instantly.

Predict future values with exponential growth. Use initial value and rate, or two data points to forecast population, investment, or bacterial growth.

Odds ratio calculator for 2×2 contingency tables: compute OR, confidence interval, Z-score, and p-value for case-control and epidemiological research studies.

Relative risk calculator for 2×2 contingency tables: compute risk ratio, 95% confidence interval, and attributable risk for exposed vs. unexposed cohort data.

Relative risk reduction calculator: compute RRR, ARR, NNT, and relative risk from treatment and control group data to evaluate any intervention's effectiveness.

Calculate relative risk (RR), absolute risk reduction (ARR), and number needed to treat (NNT). Free online risk calculator for clinical trials and epidemiology.

Calculate post-test probability using Bayes' theorem. Enter prior probability, sensitivity, and specificity to find PPV, NPV, and likelihood ratios.

P-hat calculator: enter sample size (n) and successes (x) to compute the sample proportion p̂ and its complement q̂ as decimals and percentages in one click.

Confusion matrix calculator: enter TP, FP, TN, FN to compute accuracy, precision, recall, F1-score, specificity, and MCC for binary classification models.

Calculate error propagation and measurement uncertainty for sum/difference and product/power formulas. Get absolute and relative uncertainty instantly.

Relative error calculator: find absolute error, relative error, and percentage error by comparing an observed value to the true value in any measurement.

Sampling error calculator for proportions and means. Enter sample data and confidence level to get the standard error and margin of error with FPC support.

Empirical rule calculator: enter mean and standard deviation to get the 68%, 95%, and 99.7% ranges for any normal distribution instantly.

Calculate a Yates-corrected chi-square statistic for 2×2 contingency tables. Enter a, b, c, d cell counts and get the adjusted χ² value and p-value instantly.