Use this geometric distribution calculator to find the probability of getting the first success on a specific trial in a sequence of independent Bernoulli trials. Enter the probability of success (p) and the number of trials (x) where the first success occurs. You can choose whether the value of x includes the success trial or only counts the failures before the first success. For example, this geometric distribution calculator can determine the probability that your first successful outcome happens on the fourth attempt, given a 20% chance of success each time.
The calculator displays the exact probability and related cumulative probabilities for the number of trials you enter. It also includes the mean and standard deviation of the distribution. A geometric distribution graph highlights your selected trial in red and shows the full probability distribution to help you visualize how likely each outcome is. Below the geometric distribution calculator, you’ll find additional guidance on interpreting your results. See all my Statistical Calculators!