Odds and math
Implied probability
The chance of an outcome as expressed by its odds, including the bookmaker's margin.
Odds and probability carry the same information in different notation. American odds of −150 mean risking $150 to win $100, which implies the bet wins 60% of the time. Convert with −odds ÷ (−odds + 100) for negative prices, and 100 ÷ (odds + 100) for positive ones.
The word 'implied' is doing real work: this number includes the vig, so it is always slightly higher than what the market actually believes. Add both sides of a market and you get more than 100%.
Converting a price to a probability in your head is the first skill worth building. You cannot judge a number you have not translated.
Want the full version? Read the in-depth guide, with worked examples and the math.
See also
- American odds — The +/− format used in the US, showing profit on a $100 stake or the stake needed to win $100.
- Vig — The bookmaker's built-in margin — the reason both sides of a market add up to more than 100%.
- No-vig odds — Odds with the bookmaker's margin normalised out, showing what the market actually believes.
- Breakeven win rate — The percentage of bets you must win at a given price just to avoid losing money.