Statistical Calculators
A growing collection of practical tools for experiment planning, statistical tests, uncertainty, and probability distributions.
Decision guide
Not sure which test to use?
Answer a few questions about your outcome and study design to find a practical starting point.
Test selection wizard
Question 1
What do you want to learn?
Choose the question that best matches your analysis.
Recommended starting point
Calculator collection
Experiment planning
Size a test, define a detectable effect, and choose an analysis approach.
Sample Size Calculator
Estimate the observations each group needs before an experiment starts.
Open calculator →Effect Size Calculator
Express the size of a difference in a comparable, practical unit.
Open calculator →Power Calculator
Check whether a planned or completed study can detect a meaningful effect.
Open calculator →Calculator collection
Hypothesis tests & uncertainty
Check differences, relationships, and uncertainty in observed data.
Two-Proportion P-Value Calculator
Assess evidence for a difference between two conversion rates.
Open calculator →Confidence Interval Calculator
Estimate a plausible range around an observed result.
Open calculator →Chi-Square Calculator
Test whether categorical outcomes differ from their expected pattern.
Open calculator →T-Test Calculator
Compare average values between groups or paired observations.
Open calculator →Correlation Calculator
Measure the direction and strength of a linear relationship.
Open calculator →ANOVA Calculator
Compare average values across three or more groups.
Open calculator →Calculator collection
Probability distributions
Explore the distributions behind common experiment and analytics metrics.