🎲 Probability Calculator
Calculate probability of events and outcomes
Quick Reference
P(event) = favorable / total
P(A and B) = P(A) x P(B)
P(A or B) = P(A) + P(B) - P(A and B)
P(at least 1) = 1 - (1 - p)^n
How Probability Calculation Works
Formula
P(A) = Favorable Outcomes / Total Outcomes
- 1Enter the number of favorable outcomes and total possible outcomes.
- 2For combined events, specify if they are AND (both happen) or OR (either happens).
- 3P(A AND B) = P(A) × P(B) for independent events.
- 4P(A OR B) = P(A) + P(B) − P(A AND B).
- 5Results show probability as a fraction, decimal, and percentage.
About Probability Calculator
Calculate probability of single and multiple events. Find odds, conditional probability, and expected outcomes. Supports AND, OR, and NOT operations with visual explanations.
Frequently Asked Questions
What is the difference between probability and odds?
Probability is favorable/total (e.g., 1/6 for rolling a 3). Odds are favorable/unfavorable (e.g., 1:5 for rolling a 3). A 25% probability equals 1:3 odds.
What is conditional probability?
Conditional probability P(A|B) is the probability of A given that B has occurred. For example, the probability of drawing a king given the card is a face card is 4/12 = 1/3.
Can probability be greater than 1?
No. Probability ranges from 0 (impossible) to 1 (certain). If your calculation gives a value above 1, check for double-counting or an error in the setup.