Probability Calculator
Calculate the probability of an event, odds in favor, odds against, and complement probability. Enter favorable and total outcomes to get instant results.
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Enter favorable and total outcomes to calculate probability
Frequently Asked Questions
What is the difference between probability and odds?
Probability is expressed as a fraction from 0 to 1 (or 0–100%). Odds are expressed as a ratio of favorable to unfavorable outcomes. A probability of 0.25 (25%) equals odds of 1:3.
What is the complement rule?
The probability of an event NOT happening equals 1 minus its probability. If there is a 30% chance of rain, there is a 70% chance of no rain.
What is the difference between independent and dependent events?
Independent events do not affect each other (e.g., two coin flips). Dependent events do (e.g., drawing cards without replacement). For independent events, P(A and B) = P(A) × P(B).