GLOSSARY
Arbitrage betting terms
A definition in the first sentence, then why it matters. Formulas and calculations are in the surebet calculator, a worked example is in the article “What Is a Surebet”.
Betting limits and account limitingA limit is the maximum stake a bookmaker accepts on an outcome; account limiting is cutting that limit for a specific player, usually for betting surebets.Bookmaker marginThe share a bookmaker builds into its odds on top of fair probabilities: the sum of inverse odds on all outcomes at one book, minus one.Feed groupBookmakers that get their odds from the same supplier: their prices match, and they never form surebets with each other.HandicapA bet with a notional head start or deficit added to a team's result: a −1.5 map handicap wins if the team wins by two or more maps.Live bettingBets and lines during a match; most live surebets come from one book being slow to update its line after something happens in the game.Middle betTwo bets on totals or handicaps with different lines at two books: in one outcome both win; otherwise one wins and the other is refunded or loses.Negative surebetBets on every outcome at different bookmakers where the sum of inverse odds is slightly above one: a small guaranteed loss instead of a profit.Prediction marketAn exchange where an event outcome trades as a contract priced from $0 to $1, and the price comes from traders' deals, not a bookmaker's analyst.Prematch bettingBets and lines on an event before it starts; prematch surebets live longer but appear less often than live ones.Price ageThe time elapsed since the bookmaker last updated a price that is part of a surebet.SurebetBets on every outcome of an event at different bookmakers where the sum of inverse odds is below one, so the payout beats the total stake whatever happens.Surebet legOne of the bets that make up a surebet: a specific outcome at a specific bookmaker, with its odds and stake.Surebet ROIReturn on turnover: the ratio of a surebet's guaranteed profit to the total amount staked, equal to 1 / Σ(1/k) − 1.Surebet scannerSoftware that compares odds across many bookmakers and shows events where betting on every outcome at different books pays off whatever the result.Total (Over/Under)A bet on whether the combined number of maps, rounds, kills or other events will be over or under a set line.Total killsA total on the number of kills on a Dota 2 or League of Legends map; a market where surebets live many times longer than on winners and handicaps.Total roundsA bet on the number of rounds on a CS2 or Valorant map, over or under a line such as 24.5. Books often disagree here, and overtime rules can break a surebet.Value betA bet on an outcome whose odds are higher than fair, meaning the bookmaker underestimates its probability; unlike a surebet, you can still lose.