Binomial Probability Calculator
Find the chance of k successes in n trials.
Successes in repeated trials
The binomial distribution answers a common question: in a fixed number of independent tries, each with the same chance of success, how likely is a given number of successes?
With 10 trials at a 20% success rate, the chance of exactly 3 successes is about 20.1%. Enter your own trials, successes, and probability to get the exact odds and the cumulative chance.
Exact and private
The calculation runs in your browser, so nothing you enter is uploaded.
Frequently Asked Questions
What is the binomial distribution?
It gives the probability of a set number of successes in a fixed number of independent trials, each with the same success probability.
What is the formula?
n choose k, times p to the k, times one minus p to the n minus k.
What does it show?
The chance of exactly k successes and of at least k.
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