Classical Probability Calculator
Classical Probability P(A)
Compute a probability from the definition, or quickly solve dice, coin and ball-drawing problems. The result includes the simplified fraction, decimal, percentage and the probability of the complement.
The calculator above computes the classical probability of an event as the ratio of favorable outcomes to the size of the sample space.
Formulas used
P(A) = n(A) / n(Ω)
P(not A) = 1 − P(A)
- All outcomes in the sample space must be equally likely.
- 0 ≤ P(A) ≤ 1.
Worked example
Probability of rolling an even number on a die:
P = 3/6 = 1/2
Enter the same values in the calculator above to see every step of the solution.
How to use the calculator
- Enter the number of favorable outcomes and the total number of outcomes.
- Press the calculate button. The result appears instantly.
- Read the step-by-step solution, rendered with KaTeX, to check your own work.