Probability Calculator
Solve probability problems: single events, two independent events, combinations and permutations, and binomial distributions.
Runs in your browser. Nothing is uploaded Free, no sign-up Works on mobile
Between 0 and 1
P(A and B)
0.2
20%
P(A or B)
0.7
70%
P(exactly one)
0.5
P(neither)
0.3
P(not A)
0.5
P(not B)
0.6
Assumes A and B are independent: P(A and B) = P(A) × P(B).
How to use Probability Calculator
- Choose the type of problem.
- Enter the values.
- Read the probabilities as decimals and percentages.
Frequently asked questions
What is the difference between nCr and nPr?
nCr counts selections where order does not matter (choosing a team). nPr counts arrangements where order matters (assigning first, second and third place).
How do I find the probability of A and B?
For independent events, multiply: P(A and B) = P(A) × P(B). For A or B: P(A) + P(B) − P(A) × P(B).
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