Probability Calculator
Calculate probability of single and multiple events. Free online stats tool for combinations, permutations, and odds.
About Probability Calculator
Calculate the probability of single and multiple events happening. Determine the likelihood of "A and B", "A or B", and inverse probabilities easily.
Frequently Asked Questions
What is probability?
Probability is a measure of the likelihood that an event will occur, expressed as a number between 0 and 1.
How do I interpret the results?
A result of 0 means impossible, 1 means certain, and 0.5 means a 50/50 chance.
What is P(A) and P(B)?
These represent the probabilities of two independent events, Event A and Event B.
How is 'A and B' calculated?
For independent events, P(A and B) = P(A) × P(B).
How is 'A or B' calculated?
P(A or B) = P(A) + P(B) - P(A and B). This accounts for the overlap between the two events.
Can I calculate probability from odds?
This calculator accepts decimal probabilities (0-1). If you have odds, convert them to a decimal first (e.g., 1/2 = 0.5).
Is this suitable for production statistics?
It is a basic tool for educational and quick estimation purposes. For complex statistical modeling, specialized software is recommended.
What does 'P(A) not occurring' mean?
This is the complement, calculated as 1 - P(A). It represents the chance of the event NOT happening.
Are the events assumed to be independent?
Yes, this calculator assumes Event A and Event B are independent of each other.
Is it free?
Yes, completely free to use.