Statistics Calculators
Exact statistics tools with a picture and a plain-English answer, the normal distribution with a shaded bell curve, binomial probabilities with BigInt-exact coefficients, confidence intervals, sample size, p-values from any test statistic, and least-squares regression with a scatter plot. Everything is computed in your browser, so your data is never uploaded.
- Normal Distribution Calculator Find normal-distribution probabilities and z-scores, the area below, above or between values, with a shaded bell curve, from any mean and standard deviation.
- Binomial Probability Calculator Compute binomial probabilities for n trials with success probability p, exactly P(X=k), P(X≤k), P(X≥k), plus the mean and standard deviation.
- Confidence Interval Calculator Build a confidence interval for a population mean or proportion from your sample statistics, with the margin of error and a plain-English interpretation.
- Sample Size Calculator Find the sample size you need for a given confidence level and margin of error, for estimating a proportion (survey) or a mean.
- P-Value Calculator Turn a test statistic, z, t, chi-square or F, into a p-value, one-tailed or two-tailed, using exact distribution functions.
- Linear Regression & Correlation Calculator Fit a least-squares regression line to your paired (x, y) data, slope, intercept, the equation, correlation r and r², with a scatter plot and the fitted line.
- T-Test Calculator Enter your sample means, standard deviations and sizes to run a t-test, with the t statistic, df, exact p-value and whether the result is significant.
- Poisson Distribution Calculator Enter the average rate λ and a count k to get the exact Poisson probabilities and the distribution's mean, variance and standard deviation.
- Chi-Square Test Calculator Enter observed and expected counts (goodness-of-fit) or a contingency table (independence) to get the χ² statistic, df, p-value and verdict.
- Descriptive Statistics Calculator Paste your numbers to get a full statistical summary, mean, median, mode, quartiles, standard deviation and more.
- Z-Score Calculator Enter a value, the mean and the standard deviation to get its z-score and the percentile it falls at.
- Geometric & Harmonic Mean Calculator Paste your numbers to get the geometric mean, the harmonic mean and the arithmetic mean side by side.
- Odds & Probability Calculator Convert odds to a probability, or a probability to odds, with decimal (betting) odds shown too.
- Z-Test Calculator Enter your sample mean, known population σ and size to run a z-test, with the z statistic, exact p-value and whether the result is significant.
- Effect Size Calculator (Cohen's d) Enter two groups' means, SDs and sizes to get Cohen's d, the standardized effect size, plus whether it's small, medium or large.
- A/B Test Significance Calculator Enter conversions and visitors for each variant to test whether the difference in conversion rate is significant, the A/B-test z-test.
- One-Way ANOVA Calculator Paste your groups (one per line) to run a one-way ANOVA, with the F statistic, an SS/df/MS table, exact p-value and a significance verdict.
- Mann-Whitney U Test Calculator Paste two groups to run a Mann-Whitney U test, the rank-based alternative to the t-test that doesn't assume normal data.
- Kruskal-Wallis H Test Calculator Paste your groups (one per line) to run a Kruskal-Wallis test, the rank-based alternative to ANOVA that doesn't assume normal data.
- Wilcoxon Signed-Rank Test Calculator Paste before/after pairs to run a Wilcoxon signed-rank test, the rank-based alternative to the paired t-test that doesn't assume normal differences.
Statistics with plain-English answers
These tools compute the distributions and tests that underpin data analysis, the normal distribution (z↔p via an exact error function, with a shaded curve), binomial probability with BigInt-exact coefficients, confidence intervals, sample-size planning, p-values (z, t, χ², F) and linear regression with a scatter plot. Each result comes with a short interpretation, so you know what the number actually means.
Everything is exact where it can be and computed in your browser, so your data never leaves your device and the pages work offline. For the underlying arithmetic see Mathematics; for lab and genetics stats, Biology & Lab.
Frequently asked questions
Are these statistics calculators accurate?
Yes. They use exact distribution functions (the error function for the normal CDF, the regularized incomplete gamma and beta functions for χ², t and F), accurate to about 7 decimal places. That is far beyond a printed table and more reliable than a chatbot, which routinely miscomputes p-values and confidence intervals.
Is my data uploaded anywhere?
No. Every calculation, probabilities, intervals, regression and charts, runs in your browser with JavaScript. Nothing you type is sent to a server, which matters for unpublished study data.
Do I need to install anything?
No. These are web pages that work on any modern browser, on desktop or mobile, and keep working offline once loaded.
Are these suitable for coursework and research?
Both. The tools cover the standard introductory-statistics syllabus (normal distribution, binomial, confidence intervals, hypothesis testing, regression) and give exact values researchers can report, with plain-English interpretation alongside each result.