Binomial Probability Calculator
Calculate the probability of getting exactly k successes out of n independent trials.
Calculate
Enter your values below.
Result
Probability
0
Formula used
P(k) = nCk × pk × (1−p)n−k
Example: 10 trials, 3 successes, 50% chance each → P ≈ 11.72%.
How to use this calculator
- Enter Number of trials (n), Number of successes (k), Probability of success per trial (%).
- Press Calculate to see your result instantly.
FAQ
Frequently asked questions
What is a binomial probability?
The chance of getting exactly a certain number of successes across a fixed number of independent yes/no trials.
What must stay constant between trials?
Each trial must be independent with the same probability of success.
Can k be greater than n?
No — you can't have more successes than trials.
Where is this used?
Coin flips, quality control sampling, and any repeated pass/fail experiment.