The d'Alembert Roulette System

 D'Alembert Roulette

The d'Alembert System uses a negative progression betting pattern, raising the bet on a loss and lowering it on a win, to turn a profit. It can be applied to any casino game that allows even-chance bets such as craps, blackjack or roulette.

The Man Behind the Math

Shortly after roulette wheels began popping up all over Western Europe, a mathematician named Jean le Rond d'Alembert sat down at his local gambling den and tried to come up with a winning strategy that used even-chance bets to beat games of chance once and for all. What d'Alembert came up with was a negative progression betting pattern that didn't require advanced calculations or record keeping. And because of its simple nature, the system that bears the Frenchman's name has remained popular to this day.

How Does the d'Alembert System Work?

This system relies on a slow, negative progression betting pattern and 'even-chance' bets. To use it at the roulette table, follow these simple steps:

  • Place 1 unit on an even-chance bet.
  • If you lose, increase the bet by 1 unit.
  • If you win, decrease the bet by 1 unit, or keep it 1 unit if you haven't lost yet.
  • Repeat until you either make a profit or hit your loss limit.
  • If you make a profit, collect your winnings and start over with 1 unit.

Best Bets for the d'Alembert System

An 'even-chance' outside bet is the only compatible choice for this particular system, because it offers an almost 50% chance of winning each round. Even-chance bets include, even/odd, red/black or high 18/low 18. Each pays 1/1.

How This System Translates to the Roulette Table

Let's have a look at how the basics apply to an actual roulette scenario. You stroll into your favorite casino or login online to put this system to the test.

  • You begin the session by choosing a 1 unit bet of C$5 and lay a chip on black.
  • The wheel spins around and around until the ball lands in the 24 black pocket for a win. Since the payout is 1/1, you profit C$5. Due to the win, you pocket your profit and place 1 unit on black.
  • The wheel spins again, only this time 18 red is selected resulting in a loss of C$5. You add another unit to your initial bet for a total of $10 on black.
  • This time, the ball lands in the 4 black pocket for a win. You collect your winnings and place 1 unit on black for a total bet C$5 going into the next spin. At this point in the session, you have a net profit of C$10.

Notice how the bet progression only goes up or down exactly 1 unit on a loss or win. You must follow the steps consistently throughout your session to succeed. Have a look at how a more extended session plays out.

Total Bet Win/lose # of units Net Profit
C$5 Lose +1 -C$5
C$10 Lose +1 -C$15
C$15 Lose +1 -C$30
C$20 Lose +1 -C$50
C$25 Win -1 -C$25
C$20 Win -1 -C$5
C$15 Win start over C$10

The Logic Behind the d'Alembert

Mathematically speaking, the odds given by even-chance bets amount to around 47% when taking into consideration the 2.5% to 5% house edge. On a long enough timeline, for argument's sake infinity, each pocket on the roulette wheel will have seen the same number of hits as every other pocket. When used long term, this system ultimately loses due to the house edge.

Playing in real-time gives players the opportunity to use the d'Alembert system to exploit the short term variance that we see when playing tableside. The basic thought behind increasing your bet on a loss is to help recover that loss as well as make a small profit in the event the next spin wins. Decreasing the bet on a win allows you to keep some profit even if the next spin results in a loss.

d'Alembert designed this system with the theory that a win was certain to follow a loss due to the probability of even-chance bets. As we have already established, real-life sessions don't play out the same as imaginary sessions with thousands of spins and a bottomless bankroll. d'Alembert didn't take into account the house edge or the short term variance of winning/losing streaks.

That's why most experienced gamblers keep this strategy short term and quit when they profit. It is most effective when losing streaks are only 3-4 spins long and followed by almost the same number of wins.

Main Advantages of This System

The d'Alembert system's biggest advantage is that the bet progression is relatively slow. You certainly won't be likely to hit any table limits in event of a losing streak. This allows for greater flexibility in where you choose to play.

It's definitely something to remember when considering whether or not to use this over other systems, such as the Martingale, that rely on doubling bets. Double bet progression requires a very large budget and a generous table limit to have any chance of success.

Some Points to Consider

Though this type of roulette system boasts minimal risk, it also comes with relatively low reward potential. Also, the longer you play, the less successful it is likely to be due to the house edge. Reducing the bet after wins and increasing after losses may help gain a bit of profit in a few spins, however, it doesn't play out well after a longer losing streak or initial winning streak.

Like any roulette system, the d'Alembert is meant for short-term use for best results.

Does the d'Alembert System Really Work?

How well does this system normally play out? Well, fairly well if you start off losing and then win. Not as well if you start off winning, and then hit a losing streak. This is because you have to keep the bet at 1 unit on wins which doesn't cushion any losses to follow. Have a look at these examples.

This is what happens when you lose 3 spins at the start of a session, then win 2:

Round Bet Win/Lose Net Profit
1 C$1 Lose -C$1
2 C$2 Lose -C$3
3 C$3 Lose -C$6
4 C$4 Win -C$2
5 C$3 Win C$1

This is what happens when you win 3 spins at the start of a session, then lose 2:

Round Bet Win/Lose Net Profit
1 C$1 Win C$1
2 C$1 Win C$2
3 C$1 Win C$3
4 C$1 Lose C$2
5 C$2 Lose C$0

With a bit of luck, you can turn this system to your advantage at the table. Keep sessions short. The d'Alembert works best with a roughly even number of wins or losses, so quit while you are ahead. It really doesn't recover well from longer losing streaks than 3 or 4, so take that into account before using it.

Most experienced gamblers agree that while the profits may not be mind-blowing, the risk is minimal enough to make this a must have in every gambler's repertoire of roulette strategies.

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Gamble Responsibly

  • Though this system uses single unit, low risk bets, players that struggle with keeping to personal budget limits may find this, or any roulette system, a challenge to use effectively.
  • Count the cost before beginning each session. Make a plan and stick with it.
  • The wheel spins again, only this time 18 red is selected resulting in a loss of $5. You add another unit to your initial bet for a total of $10 on black.
  • While this system offers a low risk bet progression, nothing is guaranteed to work. Remember its weaknesses and change your gameplay accordingly.

Is This the Right System for You?

If you are looking for a low risk, low reward strategy for your modest budget, the d'Alembert System would make a terrific fit. The rules are simple to follow, and you won't dig yourself into a hole too quickly with its slow bet progression. As it doesn't work as well at recovering from longer losing streaks, many gamblers tend to alternate between this and riskier strategies at the casino.

The Contra d'Alembert

If you think the d'Alembert system fits your style, but want to get shake things up, then give the Contra/Reverse d'Alembert strategy a spin. This variation on the d'Alembert system requires you to add a unit after a win and remove a unit after a loss. The main disadvantage is that it is less likely to profit even if there are more wins than losses when the session begins on a winning streak.

Round Bet Win/Lose Net Profit
1 C$5 Win C$5
2 C$10 Win C$15
3 C$15 Win C$30
4 C$20 Lose C$10
5 C$15 Lose -C$5
6 C$10 Win C$5
7 C$15 Lose -C$10

If your session starts with a winning streak, it works best to end the session after hitting a loss and pocket the profit. Then, start over. If the session above had ended after round 4, the profit would have amounted to 2x the initial bet.

The Aggressive d'Alembert Variation

This variation on the original keeps all the same rules with one exception. It instructs you to make the most of a winning streak by not reducing the bet after a win. You must bet the same amount until you get a loss. Have a look at this example.

Round Bet Win/Lose Net Profit
1 C$5 Lose -C$5
2 C$10 Lose -C$15
3 C$15 Win C$0
4 C$15 Win C$15
5 C$15 Win C$30
6 C$15 Win C$45
7 C$15 Lose C$30

Under the right set of circumstances, the end result can be much more profitable.