Implied Probability
Implied probability is the chance of an outcome that a set of betting odds represents, converted from the price into a percentage.
Every odds price encodes a probability — the break-even win rate at which a bet on that price is neither profitable nor unprofitable. Converting odds to implied probability lets you compare prices across formats and books, and is the first step in nearly all betting analytics: value detection, devigging, and EV all start by turning prices into probabilities.
For American odds the conversion depends on sign. For negative odds (favorites): implied probability = (−odds) / (−odds + 100). For positive odds (underdogs): implied probability = 100 / (odds + 100). So -150 implies 150 / 250 = 60%, and +200 implies 100 / 300 = 33.3%. For decimal odds the formula is simply 1 / decimal — decimal 1.91 implies 52.4%.
Raw implied probabilities include the sportsbook’s vig, so the two sides of a market sum to more than 100%. To recover the market’s true estimate you must remove the margin (see no-vig odds), which rescales the probabilities to sum to exactly 1. The gap between raw and no-vig implied probability is the book’s edge on that market.