Sports Betting Terms: Gambling Glossary


Accumulator wagers (or parlay bet in North America) consist of two or more selections combined inside a single bet. Each side must win to create an overall winning ticket.
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Arbitrage in investing is the simultaneous purchase and sale of the same or similar asset in different markets in order to profit from tiny differences in the asset's listed price. Arbitrage exploits short-lived variations in the price of identical financial instruments.
Arbitrage, often shortened to ARB, can also be applied to sports betting. Arbitrage wagering is a betting strategy where all possible outcomes of a single game are covered, and profit of differences and variations between different bookmakers.

Bad Beat

A bad beat is when a bet is just about to win but then becomes a losing ticket.
Using math based betting strategies lead to mitigate the occurence of bad beats.
See also "secure your bet".

Betting strategy

Various plans that bettors can use to increase their chances of winning or the payout. See the list of such plans.
Betting strategies should include proper bankroll management and long-term calculations.


A bookmaker, or sportsbook, is a licensed individual who sets betting odds and accepts bets.
Also, in short, bookie or book.

Decimal odds

An odds format, common in Europe. Other odds formats are fractional and American odds.
Read more about odds, payouts calculations, format converter,…


Dutching is a mathematical betting technique which consists of distributing an overall stake over several events in order to ensure a constant fixed gain whatever the prediction which will be the winner.
Strategic wagers can thus be made on every bet, altogether, increasing chances of making a profit.
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Elo rating system

The Elo rating system is a system for evaluating the relative level of players. It is actually a real mathematical model for evaluating the strength of competitors in a discipline.
In particular, from the Elo ranking, the the probability of victory for each opponent can be simply and directly calculated. A essential tool for any bettor!
Elo rating system in sports betting

Mathematical construction of the Elo rating system

Expected value / standard deviation

Expectation and standard deviation are the two fundamental mathematical indicators in statistics and probability.
Expectancy estimates the long-term average gain.
Standard deviation estimates the risk in a bet: a high standard deviation means large potential gains but also large losses.
Math expected value

Standard deviation

Fractional odds

An odds format, common in the UK. Other odds formats are decimal (common in Europe) and American odds.
Read more about odds, payouts calculations, format converter,…

Kelly criterion / formula

The Kelly criterion is a mathematical formula that allows you to estimate the exact amount of the optimal stake to wager. Kelly's bet leads to a higher bankroll, or capital, than any other long-term strategy.
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Simple bet / multi bet / bet system

A single bet is a bet on one outcome of a single event, for example the victory of one team against another.
Several betting strategies exist to accumulate single bets, combine bets, ...
Bookmakers are increasingly offering such ready-made betting strategies, looking for to attract more bettors.
An additional commission may be charged by bookmakers offering these ready-made betting systems. It can thus be really advantageous to build your own betting strategies using different betting formulas such as the following:

Parlay bet (also Accumulator bet, or multi)

Parlay bets, or accumulator wagers, consist of two or more selections combined inside a single bet. Each side must win to create an overall winning ticket.
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Double chance

The double chance bet is a betting formula that balances the risk taken and the expected gain.
A double chance bet is when you bet on two of the possible outcomes (usually two out of three, in a soccer bet). You get the winnings probability obviously increased. For example, in a soccer match, you bet both on win and draw: if your team wins, you win, and if the game ends in a draw, you also win !
Of course, for this to work, it is not a question of betting any bets on the two results, so as not to transform a double chance of winning into a double chance of losing!
Learn more on double chance bets…

"Refunded if" method, also known as "Draw no bet"

The "Refunded Si" betting strategy allows you to secure your bet: you bet twice on 2 different outcomes of the same sport event: in one of the two cases you win, and in the 2nd you are stacked back, that is your lost investment is refunded!
Enough to keep bad beats away, quite simply!
Of course for this to work, the two bets must be calculated exactly according to the odds of each outcome.
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A Trixie bet is a popular form of multiple bet in sport betting. It involves three selected events combined in 4 bets.
This bet type allows you to seek a strong gain, by creating significant odds (thanks to accumulator bets), while minimizing risks. The trixie is therefore a very appreciable compromise, high gain / low risk.
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Mathematical tips for securing multiple bets

Multi (or accumulator, or also parlay) bets are very attractive thanks to the high odds they provide, but are on the other hand very risky.
It is nevertheless possible to secure such bets, with some mathematcics and a little monitoring of the results.
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2 of 3 system (also 2/3 bet)

You are more likely to win by playing twice than once... that's exactly the idea behind the system 2 of 3.
In a 3-way sport event (for example 1x2: victory/draw/loss), you bet 2 times, on 2 outcomes.
The chances of winning are consequently increased! In counterpart, the winnings are reduced in accordance.
On the other hand, it is not a question of betting any amount on the two bets…
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2 of 3 system, bookmaker variant

A variation of the 2 of 3 betting system above, in which the bookmakers are compared and also compete with each other (principle of arbitrage, or ARB).
We always seek to increase the chances of winning, and in addition here to also increase the gain itself.
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Money race

A money race is a betting strategy in which the profit amount from a winning bet is invested directly in the next bet. This race is usually continued through successive bets until a desired amount of money is reached.
The objective is simple: to multiply the odds together as well as the winnings.
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A martingale is a strategy of betting on several consecutive bets: you bet or not, an amount which depends on the previous results.
In this betting system, it is therefore history which dictates futur behavior and bets.
The ultimate goal is clear: to win every time (more precisely in every series): be careful, an uncontrolled martingale can clearly backfire on its author and lead to significant losses.
A strategy to study calmly and in depth

Miller's method

Deciding the right amount to bet is an important step.
The Kelly Criterion is a mathematical formula for calculating this exact optimal amount. Certainly, but this formula is far from simple and immediate to use.
The Miller method is a strategy that simply and effectively gives you the amount to bet according to your bankroll.
Read more on Miller's betting strategy …


An essential part of any bet!
Odds (decimal format) are shown as one number, which is the amount a winning bet would collect on a €1 bet. For example, with odds of c = 2.3, a winning bet would receive €2.3 profit for an original €1 bet.
Odds between 1 and 2 are favorite bet.
Even more essential to know: odds also represent the probability of an event happening: mathematically, the odds are the reciprocal of the probability of winning.
Read more: odds & probability …

Probability / chance

A key term... of course when you bet, you are lucky… or not…
The mathematical concept and the calculation of probabilities allow us to go further than simple “chance or not”.
In particular by focusing not on a single bet, but on several, that is to say on long-term effects and on overall strategies.
The mathematical law of large numbers makes it possible to equate the probability of an event with its frequency of occurrence when a random experiment is repeated a large number of times.
Indeed, the interesting characteristic of a sports bet, or a strategy of betting, is not directly the probability of a sporting event, but its adequacy with the gain that it can provide. The mathematical expectation is the appropriate mathematical tool for calculating this: how probabilities and payoffs balance out (or not).

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Odds & probability in sports betting

Math: expected value


The math expectation and the standard deviation make it possible to predict, in the long term, random results.
On the contrary, ROI and ROC returns are a posteriori mathematical indicators. They make it possible to judge the effectiveness, or not, of a strategy, of a betting season, etc.
Enough to measure, for example, if a strategy and/or a tistper are really effective.
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Secure a bet

To secure a bet means to decrease the probability of loss.
A number of betting strategies can be used to achieve this.
Actually, a bettor with long term winnings view should always look for secure bets.
Of course, reducing the risk of loss has a price: also reducing the profit, in the same way that insurance works.
A typical example of strategy which secure a bet is the refunded if (also "draw no bet") strategy where you wager twice, on two different outcomes: you normally win with one outcome and get stacked back, or refunded, if the second one happened.


The amount of money a bettor risks when placing a bet.
The stake is entirely lost for a bad pronostic, whereas for a successful bet the payout is calculated by multiplying stake by the odds. Read more


It's just, literally, a bet which is sure.
Surebet refers to bets that result in a sure win, regardless of the actual result.
Let's make it clear right away that this is not a magic tip, but is the result of a clear mathematical calculation in a specific situation (which is not that common...)
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A person or group that regularly offers betting advice.
Of course, not all advice is necessarily good to follow... and a period of follow-up, a significant history and statistics can help to sort it out.


A value bet, or also "profitable bet", is a bet on an outcome whose odds have been overestimated by the bookmaker. This is in theory the only case of simple betting where a bettor should bet with the expectation of long-term winnings.
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