📊 Probability Calculator
Calculate probabilities for single events, multiple events, conditional probability and normal distribution
Single Event Probability
Results
Probability
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Complement (Not happening)
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Odds
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Two Events Probability
Results
P(A ∩ B) - Both occur
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P(A ∪ B) - At least one occurs
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P(A' ∩ B') - Neither occurs
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P(A XOR B) - Exactly one occurs
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Conditional Probability
Results
P(A|B) - A given B
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P(B|A) - B given A
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Normal Distribution
Results
Z-Score
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Cumulative Probability P(X ≤ x)
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Confidence Interval
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Formula Used:
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Steps:
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Frequently Asked Questions
Probability is a measure of the likelihood that an event will occur, expressed as a number between 0 and 1, where 0 means impossible and 1 means certain.
If A and B are independent events, multiply their probabilities: P(A and B) = P(A) × P(B). If they're dependent, you need P(A and B) = P(A) × P(B|A).
Intersection P(A ∩ B) is the probability that both events occur. Union P(A ∪ B) is the probability that at least one event occurs.
Use the formula P(A|B) = P(A ∩ B) / P(B), which gives the probability of A given that B has occurred.
With fair dice, it's 1/6 × 1/6 = 1/36 ≈ 2.78%. Each die roll is independent with probability 1/6.
If odds are "1 in X", the probability is 1/X. For example, 1 in 4 odds = 1/4 = 0.25 = 25%.
Normal distribution calculates probabilities for continuous data that follows a bell curve pattern, using mean and standard deviation.
No, probability must be between 0 and 1 (or 0% and 100%). Values outside this range indicate an error in calculation.
⚠️ Disclaimer
This calculator is for educational and reference purposes only. The results are based on mathematical formulas and input parameters. In real-world applications, there may be additional factors that affect probability. Please consult with professionals when making important decisions based on probability calculations.