Probability Calculator

Calculate the probability of single and multiple independent events.

Single Event

Favorable Outcomes

Total Possible Outcomes

Multiple Events (Independent)

P(A) — Probability of Event A

P(B) — Probability of Event B

Single Event Results

P(Event)

P(NOT Event)

Multiple Event Results

P(A AND B)

P(A OR B)

P(A XOR B) — Exactly one

How It Works

For a single event: P(Event) = Favorable Outcomes / Total Possible Outcomes. P(NOT Event) = 1 - P(Event). For two independent events A and B: P(A AND B) = P(A) × P(B), P(A OR B) = P(A) + P(B) − P(A AND B).

P(A) = favorable / total | P(A ∪ B) = P(A) + P(B) − P(A ∩ B)

About this Calculator

The Probability Calculator is a free, easy-to-use tool for chance, odds, events. Simply enter your values and get instant, accurate results — no signup, no ads, no tracking. All calculations run locally in your browser, so your data stays completely private.

Privacy Note: All calculations are performed locally in your browser. No data is ever sent to a server or third party.