Probability Calculator

The probability of event A, as a decimal between 0 and 1. The events are assumed independent — A happening does not change B’s chances.

The probability of event B, also between 0 and 1 — e.g. 0.3 for a 30% chance.

The chance of success on each single attempt. Small per-trial chances add up: at 0.1 per trial, 10 trials give about a 65% chance of at least one success.

How many independent attempts are made. More trials push the chance of at least one success toward 1.

The probability that A and B both happen. It cannot exceed P(B), since “A and B” is contained in B.

The probability of the conditioning event B. The result is P(A | B) = P(A and B) / P(B).