Contra Bet Roulette System Guide | LeoVegas

Contra Bet Roulette System

The Contra Bet Roulette, also known as the reverse D’Alembert system (or Contra D'Alembert betting system), is among the favourite strategies of roulette players.

The core of the strategy is this - increase your bet by one unit if you win, and decrease your bet by one unit if you lose. The strategy uses the concept of even money bets, meaning there are only certain types of bets that can be used if implementing this type of gameplay, which we will look at in further detail.

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As we move through this article and the explanation of the Contra Bet Roulette system, we will look at the system, its meaning, origins of and the principle behind the strategy, as we delve into how likely it is that you can win on roulette by using this method.


The Basics of Contra Bet Roulette

As with all roulette strategies, you will need to bear in mind that European roulette or French roulette are different to American roulette. This is simply because American roulette spins with a 0 and a 00 pocket, increasing the house edge from 2.7% to 5.26%.

Origins and History

Like many of the systems of playing roulette we know, the Contra Bet or Reverse D’Alembert system, dates back to the 18th century and the work of French physicist Jean-Baptiste le Rond d'Alembert.

As with other theories and strategies of playing roulette, or any game of chance, there was no system designed that guaranteed a win - you are playing a game of chance, after all. But there are some interesting features of the Reverse D’Alembert system that we can look at to see how they can be applied to your roulette playing.

Core Principles

The Contra Bet, or Reverse D’Alembert, is the exact opposite of the D’Alembert system applied to playing roulette.

The regular D’Alembert applies the theory of increasing your stake by a unit when you lose, and decreasing it when you win. The Reverse D’Alembert literally does the opposite, aiming to capitalise on a ‘winning streak’ and implementing the strategy of Positive Progression. As with any way of playing roulette, or gambling, you still need to choose your stake - remember to choose one that suits your budget and always gamble responsibly.

Turning around D’Alembert aims to have a positive impact and turn a negative progression into a positive one. Having success with the Contra Bet method relies on a series of winning spins, but unlike the standard D’Alembert, a string of losses may take longer for you to reach your loss limit, which it is of course important to set.

Mechanics of Contra Bet Roulette System

As mentioned, the betting process of the Contra Bet system relies on a Positive Progression framework, meaning you increase your stake at times of winning. You firstly need to start with a base stake, for example $1. Though this system decreases a stake with each loss, should you lose on your base stake, you keep playing with this amount of money until you either have a winning round, or you reach your loss limit.

A series of bets on the Contra Bet Roulette system could go like this:

Stake/td> ResultOverall
$2/td> Win+$4

As you can see, in this series, the player is $3 in profit after seven games of roulette, with the Positive Progression here seeing at one point a profit of $10 - yet the increased stake upon winning sees profits almost half in one losing spin. An example of no matter the strategy you take, a game of chance remains just that.

When it comes to managing risk, the Contra Bet strategy can be viewed as so, due to the reduction in stake while on a losing streak. No strategy however is risk free - that is the nature of the game!

Pros and Cons of Contra Bet Roulette System

As with any system or strategy, there are both advantages and disadvantages to utilising the Contra Bet Roulette, or reverse D’Alembert system while playing roulette. Let’s outline these below.


  • Simplicity: The Contra Bet system is straightforward to understand and implement, due to the increase or decrease in stake with each play. This makes it accessible to both novice and experienced roulette players.
  • Can minimise risk: As strategies go, this one is considered a strategy that can help to manage risk. Though of course not risk free, this is gambling, the strategy of increasing bets after a win and decreasing them after a loss can help reduce losses in the short term.
  • Slow Progression: The system's gradual betting progression can help players manage their bankroll and extend their playing time at the roulette table. Building on a positive progression can also lead to wins when on a winning streak.

Disadvantages and Risks

  • No Guaranteed Wins: Like all betting strategies, the Contra Bet system does not guarantee consistent wins in the long run. While winning streaks using the increased bet after a win can yield profit, as we have seen this can quickly change due to the nature of gambling. Roulette is a game of chance, and there is no foolproof way to beat it.
  • House Edge: While the system relies on evens or double-your-money bets, there is no getting away from the fact that the chance is not completely 50/50. Roulette has a built-in house edge, even more so on the American game, and no betting system can change the fundamental odds of the game. Due to this, as the game goes on, the house edge will still work against the player.

Other Roulette Betting Systems


The opposite of the Contra Bet strategy, the D’Alembert system, increases bets with a loss and decreases with a win, in an attempt to mitigate loss. By increasing your bet when you lose and decreasing it when you win, the system aims to recover losses gradually and potentially secure small profits.


The Martingale system is based on the idea of doubling your bet after each loss, with the goal of recovering your previous losses and making a profit. The theory behind this strategy relies on the belief that eventually you will win a bet, recoup your losses and be rewarded with a profit.

The Martingale system requires a substantial bankroll, due to the doubling of the bet after a loss - this can get into big numbers very quickly. Again, a winning game is not inevitable in the game of chance that is Roulette. Be sure to stick to your loss limit and only set gambling budgets you can afford.


A positive progression system, the Paroli system in Roulette involves increasing your bets after a win and resetting them to the initial amount after a loss. After each win your stake would double, and upon a loss would revert back to the original bet amount until another winning round is achieved. As bets are only increased with winnings, this can be considered a lower risk strategy, but it is imperative that you set a limit for how many losing rounds you can afford - nothing is guaranteed and a long losing streak can result in big losses.

Learn about other roulette strategies in our guide: