Free, accurate statistical calculators for everyone.
Statistical analysis should not require expensive software or a PhD. Stat-Tools was built to give students, researchers, healthcare workers, business analysts, and curious minds instant access to professional-grade statistical calculators — completely free, no sign-up required.
Every calculation runs on a Python/SciPy backend — the same numerical library trusted by scientists worldwide — so you get the same accuracy as SPSS, R, or Stata, directly in your browser.
Mean, median, mode, standard deviation, variance, IQR, skewness, kurtosis, and more from raw data.
One-sample, two-sample independent, and paired t-tests with p-value and plain-English conclusions.
CI for a population mean (t-distribution) or proportion (z-distribution).
Required sample size for estimating a mean or proportion at a given confidence and margin of error.
PDF, CDF, z-scores, and tail probabilities for any normal distribution.
Pearson and Spearman correlation coefficients with p-value, 95% CI, and scatter plot.
Slope, intercept, R², residuals, and regression line chart.
Goodness of fit and independence tests with Cramér's V effect size.
F-statistic and p-value for comparing means across three or more groups.
All calculations are performed server-side using Python 3.12 with SciPy 1.18 and NumPy 2.5 — the standard scientific computing libraries used by researchers, data scientists, and engineers worldwide.
Results should match those produced by R, SPSS, Excel (Analysis ToolPak), and other standard statistical software. If you find a discrepancy, please contact us.
Questions, bug reports, or feature requests? Email us at plescadenis86@gmail.com.
Stat-Tools is not a substitute for professional statistical consulting. Results should be interpreted by someone with appropriate statistical knowledge for critical research or business decisions.