Calculate probabilities for single events, combined events (AND / OR), and complementary outcomes using decimal or percentage values.
Result:
Copied

About Probability

Probability measures the likelihood of an event occurring and ranges from 0 (impossible) to 1 (certain). It is widely used in statistics, science, finance, and everyday decision-making.

How This Calculator Works

You can calculate probabilities for a single event, the chance that two events happen together (AND), the chance that at least one event happens (OR), or the complement of an event (NOT A).

Formulas Used

Single: P(A)
AND: P(A) × P(B)
OR: P(A) + P(B) − P(A)×P(B)
Complement: 1 − P(A)

Practical Advice

Always ensure probabilities are realistic and between 0 and 1. This tool assumes events are independent when using AND and OR calculations.

FAQs

Can I use percentages? Yes, values above 1 are treated as percentages.
Are dependent events supported? This calculator assumes independence.
Is this exact? Results are mathematically accurate based on the input.