Probability Calculator
Type probabilities as decimals (0.5), percentages (50%) or fractions (1/6). The events are assumed to be independent, like two dice or two coins.
Repeated tries
How to use it
- Type the probability of each event.
- Read the probability of both, either, exactly one or neither.
- For repeated tries, type the chance per try and the number of tries.
Frequently asked questions
What does independent mean?
The result of one event does not change the chance of the other, like two separate dice. Then P(A and B) = P(A) × P(B) and P(A or B) = P(A) + P(B) − P(A) × P(B).
What is the chance of at least one success?
It is 1 minus the chance of failing every time: 1 − (1 − p)ⁿ. For example, the chance of rolling at least one six in 4 rolls is 1 − (5/6)⁴ ≈ 51.8%.
Why is the chance not just p times n?
Because successes can happen more than once and would be counted twice. With p = 1/6 and n = 6, p × n gives 100%, but the real chance of at least one six is about 66.5%.
🔲 Matrix Calculator
🟰 System of Equations Calculator
🎲 Permutation and Combination Calculator
📶 Binomial Distribution Calculator
🔔 Normal Distribution Calculator
ℤ Z-Score Calculator
➗ Long Division Calculator
📊 Standard Deviation Calculator