Fixed-odds betting

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Fixed-odds betting is a form of gambling where individuals place bets on the outcome of an event, such as sports matches or horse races, at predetermined odds. In fixed-odds betting, the odds are fixed and determined at the time of placing the bet. These odds reflect the likelihood of a particular outcome occurring. If the bettor's prediction is correct, they receive a payout based on the fixed odds. This means that the potential winnings are known at the time of placing the bet, regardless of any changes in the odds leading up to the event.

Fixed-odds gambling involves placing bets on events with predetermined odds. Bookmakers aim to create an overground, where the sum of probabilities quoted for all possible outcomes exceeds 100%, ensuring profit. Imbalanced books can occur, leading to higher or lower payouts than expected. The advent of the internet and betting exchanges has led to opportunities for fixed-odds arbitrage actions and Dutch books.

When a bet has a positive expected value, it is said to be getting "the best of it." In contrast, "laying odds" refers to a bet in which more is risked than can be won, and rational bettors only engage in this type of bet if the chances of an adverse outcome are low enough. "Lay betting" is when a bettor bets against a specific outcome, effectively taking on the role of a bookmaker.

Odds can be expressed in various formats, including fractional, decimal, and moneyline. Fractional odds are used primarily in the United Kingdom and Ireland, while decimal odds are favored in Continental Europe, Australia, New Zealand, and Canada. Moneyline odds are used in the United States. Converting between these formats requires specific calculations depending on the type of odds used.