Probability Calculator (Single Event)

Calculate the likelihood of a single event occurring.

Number of Desired Outcomes (Event A):

Total Number of Possible Outcomes:

Enter the number of ways the specific event you're interested in can happen ('Desired Outcomes').
Enter the total number of possible outcomes in the situation.
Click "Calculate Probability".
The calculator shows the probability of the event happening (P(A)) and not happening (P(A')) as a fraction, decimal, and percentage.

Example: Rolling a 4 on a standard six-sided die.

For a single event A:

P(A) = (Number of Desired Outcomes) / (Total Number of Possible Outcomes)

The probability of the event *not* occurring (complement P(A')) is:

P(A') = 1 - P(A)

Probability values always range between 0 (impossible) and 1 (certain).

Probability Results: