Probability and Odds Conversion Calculator

This Probability and Odds Conversion Calculator can be employed for converting probabilities into odds or the other way around. Just click one of the buttons and input either a probability for converting into odds or odds for converting into probability.

Probability-Odds Conversion Calculator

Probability vs. Odds

Any chance can be numerically described as either odds or probabilities. In the majority of circumstances, neither is preferable to the other. The majority of scientists generally refer to probabilities, not odds, but that is more a matter of tradition, there is no logical basis for it.

There's a simple difference between probabilities and odds: the probability of an event occurring is a fraction of how many times you would expect to see that event occurring on a set number of occasions. A probability is always expressed as a number between 0 and 1. Odds on the other hand are expressed as the likelihood of an event occurring divided by the likelihood of it not occurring.

Probabilities of 0 are the same as odds of 0. If the probability is between 0 and 0.5, the odds will be below 1.0. If the probability is exactly 0.5, then the odds are 1.0. Think of flipping a coin; it will come up heads 50% of the time, making the probability of it happening 0.5 (50% of 1). This makes the odds of it happening 1.0 (50÷50).

When probability rises from 0.5 to 1.0, odds rise from 1 to a number approaching infinity. As an example, if we have a probability of 0.8, that makes the odds 8/2, which we can reduce to 4/1, which equals 4.0.

When the odds are very high, e.g. 1000/1, probability is close to 1.00. Conversely, if odds are very small (1/1000), probability will also be very small, close to 0.

Probability/Odds Conversion

Converting probabilities into odds, we simply divide the probability by 1 less the probability, e.g., if the probability is 25% (0.25), the odds are 0.25/0.75, which can also be expressed as 1 to 3 or 1/3 or 0.333.

Odds/Probability Conversion

Converting odds into probability, we divide the odds by 1+ the odds e.g., if we have odds of 1:3, then we divide 1/3 by 4/3 which gives us a probability of 0.25 or 25%.

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