At least one probability calculator
Enter probabilities as values from 0 to 1.
Branch probabilities
Bars show the calculated outcomes.
Calculation branches
| Event | Probability |
|---|---|
| Fill in the fields above — the result is computed on this page. | |
How do I use this page?
- Enter inputs.
- Check the branches and formula.
What this page does not do: The result assumes the supplied conditional probabilities are correct; repeated-trial mode assumes independence.
Further reading
Theory — how is the probability of at least one event calculated?
This calculator estimates the chance that at least one of several independent events occurs. Probabilities are entered as decimal values between 0 and 1, so 25% becomes 0.25. The tool applies the complement rule together with the multiplication rule: it first finds the probability that none of the events happen, then subtracts that result from one, showing every intermediate step.
Frequently asked questions
Can I enter percentages?
See also
A/B test calculator
Compare two proportions in an A/B test. Calculate conversion rates, difference, uplift, z score, p value and c
A/B test planning — sample size, MDE and duration
Plan a two-proportion experiment, estimate detectable effect and traffic duration.
ACF and PACF autocorrelation calculator
Calculate ACF and PACF across time-series lags. Review the chart, reference bounds and coefficient table.