Probability Calculator
Calculate probability of single events, multiple events, conditional probability, and more.
Calculator
Results
Enter values and click Calculate
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How to Calculate Probability
To calculate the probability of a single event, divide the number of favorable outcomes by the total number of possible outcomes. For example, the chance of rolling a 3 on a six-sided die is 1 ÷ 6, which is about 0.167 or 16.7%. Expressed as a probability percentage, the result makes it easy to compare the likelihood of different outcomes.
The conditional probability calculator handles the case where one event depends on another, using the formula P(A|B) = P(A and B) / P(B) — the probability of A given that B has already happened. For multiple independent events, the compound probability calculator combines individual chances to find the probability that several events all occur, or that at least one occurs.
The calculator also works as an experimental probability tool: enter the number of times an outcome occurred and the total number of trials, and it reports the empirical probability. Whether you need to calculate probability for homework, betting odds, or everyday decisions, you can find probability quickly with this tool rather than working through the formulas by hand.
How to Use
How It Works
Calculate probability of single events, multiple events, conditional probability, and more.
Formula / Calculation Method
This calculator uses standard mathematical formulas for accurate results.
Example
Try the calculator above with your own values to see personalized results.