The calculator will always display the implied probability of success that each set of odds represents. For example, +200 implies a probability of 33.33%, whereas -500 implies a probability of. 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.

By convention only a set of fractions are used in fractional odds betting markets. The set does not include exact mathematical equivalents to all possible decimal and American odds. We use the closet fraction that is used in betting markets.

For example, the exact mathematical equivalent of decimal odds 30 is fractional odds 29/1. However 29/1 is not used in betting markets, instead 30/1 is used, so that is what appears in this converter.

For an explanation of the odds types on this table see decimal, fractional and American odds. To find out what the numbers really represent see understand odds as probability with overround.

Converting Between Probability And Odds