Statistics

Probability Calculator

Calculate single event probabilities, joint outcomes, conditional odds, and complementary chances.

Reviewed & Maintained by

Aadil Malik — Software Engineer

1 min read · 21 words

What is a Probability Calculator?

A probability calculator solves single-event probabilities, compound independent events, union rules, and conditional odds distributions.

Probability is the measure of the likelihood that an event will occur, expressed as a number between 0 (impossible) and 1 (certain).

P(A) = Number of Favorable Outcomes / Total Number of Possible Outcomes.

P(Not A) = 1 - P(A).

P(A and B) = P(A) * P(B).

P(A or B) = P(A) + P(B) - P(A and B).

P(A|B) = P(A ∩ B) / P(B), representing the probability of event A given that event B has occurred.

Odds in Favor = P(A) / (1 - P(A)). Odds Against = (1 - P(A)) / P(A).

As the number of trials increases, the empirical relative frequency approaches the theoretical true probability.