🎲 Probability Calculator
Calculate the probability of a single event, or combine two events as independent, mutually exclusive, or overlapping outcomes.
Mode
Your Result
Probability
16.67%
Fraction
–
Odds
–
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How the Probability Calculator Works
Probability measures how likely an event is to occur, expressed as a number between 0 (impossible) and 1 (certain), often shown as a percentage.
Formulas
Single event: P = favorable outcomes / total outcomes
Independent (A and B): P(A) × P(B)
Mutually exclusive (A or B): P(A) + P(B)
Not mutually exclusive (A or B): P(A) + P(B) − P(A) × P(B)
Independent (A and B): P(A) × P(B)
Mutually exclusive (A or B): P(A) + P(B)
Not mutually exclusive (A or B): P(A) + P(B) − P(A) × P(B)
Frequently Asked Questions
What are independent events?
Independent events are events where the outcome of one does not affect the outcome of the other, such as flipping a coin twice.
What does "mutually exclusive" mean?
Mutually exclusive events cannot happen at the same time — for example, rolling a 2 and rolling a 5 on the same die roll. Their probabilities simply add together.
What are odds versus probability?
Probability is the chance of an event happening out of all outcomes (e.g. 1 in 6). Odds compare the chance of the event happening to it not happening (e.g. 1 to 5).