Math Calculators

Probability calculator.

Compute basic probability, combinations C(n,r), and permutations P(n,r). Choose a mode and the result updates as you type.

Inputs

Calculation mode

Favourable outcomes

Total outcomes

Result

Fill the form to see the probability.

Understanding probability

Probability quantifies how likely an event is to occur, expressed as a number between 0 and 1 (0% to 100%). The basic probability formula is P = favourable outcomes / total outcomes. Combinations C(n,r) = n! / (r!(n-r)!) count selections where order does not matter. Permutations P(n,r) = n! / (n-r)! count arrangements where order matters.