How to use this calculator
Select the distribution and calculation, then enter its parameters.
Formula and method
CDF differences give intervals; inverse CDF gives quantiles. PMF is used for discrete point probabilities and PDF for continuous density.
Worked example
Standard normal P(X ≤ 1.96) ≈ 0.975002.
Assumptions and supported scope
Normal, Student t, chi-square, F, binomial, and Poisson only. F and chi-square densities at singular zero are not calculated. Very extreme tails are limited by floating-point precision.
Method references
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