Statistics & probability
tools and calculators.
37 practical tools with clear inputs and explanations. Choose a tool below, or explore a role-based toolbox for a collection that fits your day.
Box plot builder
Compare grouped distributions, medians, spread and outliers from your own CSV.
Binomial probability calculator
Find exact and cumulative success probabilities for independent trials.
Poisson probability calculator
Explore event-count probabilities for a supplied average rate.
Normal interval probability
Find the probability inside and outside an interval under a normal model.
Normal percentile value
Find the value below which a chosen share of a normal distribution lies.
Uniform interval probability
Compare an interval with a continuous uniform distribution’s support.
Exponential waiting time
Estimate a waiting-time probability under a constant-rate model.
Trials until first success
Find the chance that the first success occurs on a particular trial.
Sampling without replacement
Find success-count probabilities when drawing from a finite population.
Bayes probability calculator
Update an event probability using evidence rates you supply.
Two-event probability calculator
Work out union, neither and conditional probabilities from an intersection.
Probability & odds converter
Translate an event probability into mathematical odds for and against.
Discrete expected value
Calculate an outcome distribution’s mean, variance and standard deviation.
Shared birthday probability
Explore the chance of a matching category in a group.
Survey sample size estimate
Plan a sample for a proportion using a supplied margin of error.
Wilson proportion interval
Calculate a bounded confidence interval for a count out of a sample.
Confidence interval for a mean
Estimate a mean interval using a sample and Student’s t distribution.
One-sample t test
Compare a numeric sample mean with a supplied reference value.
Welch two-sample t test
Compare independent sample means without assuming equal variances.
Paired sample t test
Compare matched observations by analysing their within-pair differences.
Chi-square goodness of fit
Compare observed category counts with expected relative weights.
Contingency table chi-square test
Compare two categorical variables using an observed count table.
Spearman rank correlation
Measure the association between two paired lists using ranks.
Independent-samples effect size
Compare two sample means in pooled standard-deviation units.
Geometric mean calculator
Average positive multiplicative values using logarithms.
Harmonic mean calculator
Average positive rates with an equal numerator basis.
Root mean square calculator
Calculate the quadratic magnitude of positive and negative values.
Trimmed mean calculator
Average a dataset after removing a chosen share from each end.
Median absolute deviation
Summarise spread using deviations from the sample median.
Interquartile outlier finder
List values outside configurable interquartile-range fences.
Coefficient of variation
Compare sample spread with its positive mean on a ratio scale.
Histogram frequency table
Bin a numeric list into equal-width intervals with cumulative counts.
Prediction error calculator
Compare matched actual and predicted values with common error measures.
Weighted median calculator
Find the first ordered value reaching half the total weight.
Min–max normalisation
Rescale a numeric dataset into a chosen output interval.
Standardise a numeric dataset
Convert each observation into a dataset-based standard score.
Moving average calculator
Smooth an ordered numeric series with a complete trailing window.