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Probability Calculator
Find probability from favorable and total outcomes.
The basic probability
Probability at its simplest is favorable outcomes over total outcomes. Drawing a heart from a deck, rolling a six, winning a raffle — all start from this ratio.
Thirteen hearts out of 52 cards is a probability of 0.25, or 25%, with odds of 1 to 3 and a complement of 75%. Enter your own outcomes for any simple event.
Simple and private
The calculation runs in your browser, so nothing you enter is uploaded.
Frequently Asked Questions
How is probability found?
Favorable outcomes divided by total possible outcomes, giving a value between 0 and 1.
What else does it show?
The percentage, the odds, and the complement — the probability the event does not happen.
What is the complement?
One minus the probability, the chance of the opposite outcome.
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