Probability Calculator

Calculate simple probability, odds, combinations, permutations, and conditional probability with this free probability calculator.

Calculate Probability

P(A) = 3 / 10
C(8,3) = 8! / (3!(8-3)!)
P(A|B) = P(A ∩ B) / P(B)
Your result will appear here.

How probability is calculated

Simple probability:
P(A) = favorable outcomes ÷ total outcomes

Combination:
C(n,r) = n! / (r!(n-r)!)

Permutation:
P(n,r) = n! / (n-r)!

Conditional probability:
P(A|B) = P(A ∩ B) ÷ P(B)

Why probability matters

Probability helps measure uncertainty and predict the chance of events. It is used in math, statistics, games, weather, finance, science, and decision-making.

It helps compare risks, outcomes, and expected results in a clear way.

What your result means

Your result shows the probability or counting outcome based on the selected mode. Supporting values also show percentages, odds, and formulas used.

This makes it easier to understand how likely an event is or how many possible selections or arrangements exist.

Probability calculator tips

Frequently asked questions

What is probability?

Probability is a measure of how likely an event is to happen.

What is the difference between odds and probability?

Probability compares favorable outcomes to all outcomes, while odds compare favorable outcomes to unfavorable outcomes.

What is conditional probability?

Conditional probability is the probability of one event happening given that another event has already occurred.

What is the difference between permutations and combinations?

Permutations care about order, while combinations do not.