Odds and math
Edge
The gap between your estimated probability and the probability the price implies. Positive means value.
Edge is the difference between how often you think something happens and how often the price says it happens. If you make a team 55% and the fair price implies 50%, your edge is five percentage points.
It is the closest thing betting has to a single quality score for a wager. Everything else — bet sizing, which bets to take, whether a strategy is working — follows from it.
Two cautions. Edge is only as good as the probability behind it, so a large edge from a thin model usually means the model is wrong rather than the market. And it is measured against a specific price: once the line moves, the edge you computed is not the edge you are getting.
Want the full version? Read the in-depth guide, with worked examples and the math.
See also
- Expected value — The average result of a bet per unit staked if it could be repeated indefinitely.
- Implied probability — The chance of an outcome as expressed by its odds, including the bookmaker's margin.
- Fair probability — The market's honest opinion — implied probability with the bookmaker's margin removed.
- Value bet — A bet whose price is better than the true probability of the outcome.