Implied Probability

Implied probability is the probability that a betting price implies an outcome will occur, computed directly from the odds. It's a pure mathematical translation — no model or opinion is involved.

For American odds: - Positive odds: P = 100 / (odds + 100). So +200 → 100/300 = 33.3%. - Negative odds: P = |odds| / (|odds| + 100). So -150 → 150/250 = 60%.

For decimal odds: P = 1 / decimal_odds. So 3.0 → 1/3 = 33.3%.

Implied probability is the foundation of every edge calculation: compare the implied probability at one venue (Kalshi) to a reference (book consensus, your own model, DataGolf baseline) and the difference is your edge. Positive edge means the venue is pricing the outcome too cheaply.

Note: a single sportsbook price's raw implied probability includes vig, so it's not a true probability estimate by that book. Use de-vigged probabilities for cross-venue comparison.