Probability Calculator – Favorable Over Total
Free probability calculator: enter favorable and total outcomes to get probability as a decimal and percentage. Dice, cards, events. No sign-up.
Probability Calculator
Calculate the probability of an event: favorable outcomes ÷ total outcomes.
How the probability calculator works
P(event) = favorable_outcomes / total_outcomes
Favorable outcomes must be between 0 and total. The result is shown as a decimal (0–1) and as a percentage (0–100%).
Understanding probability
Probability measures how likely an event is to occur, from 0 (impossible) to 1 (certain). For equally likely outcomes, probability = favorable outcomes ÷ total outcomes. Examples: rolling a 6 on a die (1/6), drawing a heart from a deck (13/52), or picking a red ball from 3 red and 7 blue (3/10).
This calculator assumes all outcomes are equally likely. For weighted or conditional probability, more advanced methods are needed. Use it for homework, games, and quick probability checks. For statistics (mean, z-scores, standard deviation), see our other math calculators.