Probability Calculator
What are the odds? Enter the number of favorable outcomes and the total possible outcomes to get the probability as a fraction, a decimal and a percent — plus the chance of the opposite event happening.
How to use
- Enter the total possible outcomes, like 6 on a dice.
- From these, enter the favorable outcomes, like one specific number = 1.
- You will get the probability, its percent, and the probability of the opposite event (complement).
Tips
- Favorable outcomes can never exceed total outcomes — fix your counts if the tool warns you.
- For "at least one" problems, compute 1 minus the probability of none — it is much simpler.
- Percent, fraction and decimal are the same answer — use whichever your class or report needs.
Note: Formula: P(event) = favorable / total. Favorable cannot be more than total. This is simple (theoretical) probability.
Frequently Asked Questions (FAQ)
What inputs does the Probability Calculator need?
The number of favorable outcomes and the total number of possible outcomes. Favorable outcomes can never exceed total outcomes, and the tool warns you if your counts are wrong.
What results does it show?
The probability as a fraction, a decimal, and a percent. All three are the same answer in different formats, so use whichever your class or report needs.
What is probability?
How likely an event is, found by dividing favorable outcomes by total outcomes.
Can it solve 'at least one' problems?
Not directly, but you can first compute 1 minus the probability of none, which is often the simplest way to solve 'at least one' problems.