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Testing and Analyzing Contra Bet (contra d’Alembert) System

Last updated: 01.15.2023 by Andrew Shepard

We have already reviewed and tested the d'Alembert strategy. There is also a system derived from it, called Contra Bet, or reverse d'Alembert. To understand the fundamental difference between the two strategies, we would like to draw your attention to the practical examples we derived from observing how the progression will change depending on the basic bet and bankroll. In the end, we can all agree that the Contra Bet System is based on chance, and while it has the potential to net you a big win, it also comes with certain pitfalls.

How does Contra Bet work?

The Contra Bet System is a progressive system that involves betting on even money bets (even/odd, red/black, over/under). First, we determine the baseline amount, for example, $10. So, the next thing we do is spin the wheel and see the outcome. If we win, we raise the bet by the base amount of $10. If we lose, we lower it by $10. And so, we consistently adhere to the progression. Like for d’Alembert, you can take a base rate of up to 1% of the bankroll. For clarity, we will demonstrate the strategy with an example:

Contra Bet Strategy


  • Spin 1

    You bet $10, and you lose. So, you continue betting $10.

  • Spin 2

    You bet $10, and you win, so you raise your bet.

  • Spin 3

    You now bet $20, and you win. So, you raise your bet.

  • Spin 4

    You now bet $30, and you win. You raise your bet.

  • Spin 5

    You bet $40 and lose. You lower your bet by $10 and bet $30 next time.

Our test of Contra Bet System

Let's take this progressive strategy for a test run. We change the formula from the classic D'Alembert and adjust it for Contra Bet. Let's test the system on three players who will independently play 500 moves. Everyone will play until the end of their session – if this is possible, depending on whether someone will end up breaking the bankroll earlier. We set the initial data for each player as follows:

Player # Bankroll Basic bet
1 500 5
2 1000 10
3 500 3

For the first player, we get the following result:

Contra Bet

The first player game session ends at turn 170 with a $5 bankroll. He will not have enough money to continue the progression, and he is forced to quit the game at this stage. He quickly got a positive result within a hundred spins, but the following spins weren't too good, and the player ended up in a sharp decline instead of quitting while they were ahead. Now let's see what happened with the second player:

Contra Bet strategy

The second player lasted longer. He has a larger bankroll, but the base bet is also proportionately larger. His progression lasted 469 moves and realized a $30 bankroll.

Contra Bet System

So, the result for player №3 with a $500 bankroll and $3 base bet. Here he left the game on the spin 242 with a bankroll of $15. In general, the dynamics of the game resemble the first player.

The overall dynamics of the bankroll of all three players, despite the bankroll peaks, are negative. If we return to the test of the d'Alembert system, we will notice that the dynamics there were often positive as well. What is the reason? Here, the analogy of comparing Martingale and the reverse Martingale is appropriate, where in the first case, the progression is positive, and in the second case, it is negative. It all depends on whether we increase or decrease the bet based on the previous round's outcome.

Explanation of pitfalls and when betting Contra d'Alembert

The overall progression trend is markedly negative, so success is unlikely in the long run. This is normal when you consider progressive strategies – the base bet will get bigger and bigger until you can no longer sustain it. There are risks of a sharp decline in the bankroll when the amount of the bet accumulates. At the same time, there cannot be a quick loss. As with any progressive strategy, it takes time to get results.


We tested the Contra Bet system with a strategy simulator. We took three players with different bankrolls and base rates. In addition to the illustrated examples, we launched the same players several times. The general trend of the bankroll in the long term is downward, with elements of peaks up and down. The behavior of the bankroll becomes more dynamic during those time intervals where the bet amount is the largest. At the same intervals, bankroll peaks are also visible.

Obviously, as in the case of d'Alembert, it is essential to stop in time near these peaks. But how can you know when "on time is?" There is no accurate telling, hence why this strategy relies on luck, not a particular skill. The difference is that in the case of D'Alembert, the bankroll tends to go up in the long run. Therefore, in the long term, after sufficient plays are logged in (and there's no telling what enough plays are), it is more likely to win back, according to d'Alembert. In the case of Contra Bet, it's better to try and wrap up your gameplay sooner rather than later, as it becomes more challenging in the long term.

Also, Contra Bet does not have a high risk of losing a lot of money too quickly. It is crucial to stop its progression when the bankroll amount is near the peak and significantly higher than the initial bankroll. In my subjective opinion, choosing between d'Alembert and Contra Bet, I would stock up on patience and time and choose the first. However, the choice is always yours. You can see benefits to both strategies, especially if you luck out on the Contra Bet strategy during your gameplay and end up with a sizeable bankroll that you can cash out early!

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