Probability Distribution Calculator

Compute probabilities and plot the distribution curve for Normal, Binomial and Poisson distributions — 100% in your browser.

Distribution type

Mean (μ)

Std. deviation (σ)

Value (x)

Trials (n)

Success prob. (p)

Successes (k)

Rate (λ)

Occurrences (k)

Pick a distribution: Normal — enter mean μ, standard deviation σ and value x to get the PDF f(x) and cumulative probability P(X ≤ x), with the bell curve and the shaded area to the left of x; Binomial — enter trials n, success probability p and successes k to get P(X = k) = C(n,k)·pᵏ·(1−p)ⁿ⁻ᵏ; Poisson — enter rate λ and occurrences k to get P(X = k) = λᵏ·e⁻ᵏ/k!. Each result shows the formula, the probability values (PMF / CDF / upper tail) and a chart. All math runs locally in your browser.