D’Alembert Betting System Explained

A dealer at the ‘Grosvenor Casino Leo’ prepares a roulette table for play. Oli Scarff /AFP)

The D’Alembert System is a popular negative progression strategy that tells you how much to wager when playing online casino games.

It can be applied to any bet where the chances of success are roughly 50/50, such as red/black on roulette or pass/don’t pass on craps. Read on to learn more about the D’Alembert System and decide if it is right for you.

What is the D’Alembert System?

The D’Alembert System is named after its creator, an 18th-century French mathematician called Jean-Baptiste le Rond D’Alembert. It requires you to increase the size of your bet amount after each loss, and decrease your stake after you win.

As is always the case, you should start by assigning a portion of your bankroll as your base unit amount. For example, you might have a bankroll of $200, and decide to make your base unit price 5% of that bankroll, which is $10.

You would start off by wagering one unit, or $10. If your bet wins, bet one unit again, and keep doing so until you lose.

After a loss, the idea is to increase your bet amount by one unit. If you start off by wagering $10 and it loses, your next bet would be for $20. If you lose again, you next bet would be for $30, and then for $40, and so on.

If you win, you decrease the size of your bet amount by one unit. For example, you would go back down from $40 to $30. If you win again, bet $20, and so on, until you return to one unit.

D’Alembert System Example

Let’s say you have a base unit of $20. You bet on black on a roulette wheel and the ball lands on red, meaning you are down $20. Your next bet would be for $40. If that wins, you are up $40 overall. You can then go back to betting one base unit.

If your next bet for $20 loses, bet $40. If that loses, bet $60. If your $60 wager is successful, you are up $40 overall. You can then return to betting $40. Just make sure you go up by one unit after a loss and down by one unit after a win.

A screen broadcasts a virtual roulette table. Valery Hache/AFP)

D’Alembert System Pros and Cons

The eponymous creator of this strategy believed that if a coin toss resulted in heads, that coin would be more likely to result in tails the next time it was tossed. That has since been debunked, and it is often referred to as the gambler’s fallacy.

However, the strategy remains popular. It is very simple, so you are unlikely to make a mistake and wager the wrong amount.

It does not require a particularly large bankroll and you are unlikely to run up against table limits, as you only increase your stake by one unit after each loss (by contrast, the Martingale system requires you to double your bet amount with each loss). It is low-risk and low-variance.

However, it is not quite as neat as the Martingale system, which eventually wipes out all previous losses in one fell swoop. With the D’Alembert system, you can win and still be down overall, as it is less aggressive than some negative progression systems.

You also do not really capitalize on winning streaks.

D’Alembert System Alternatives

If you prefer a more aggressive negative progression strategy, the Martingale is an obvious choice. If you are looking for something more complex, try the Fibonacci, the Labouchere or the 1-3-2-6.

You can alternatively go for a positive progression strategy, such as the Paroli or the Reverse Martingale. They do not chase losses, but they do reward winning streaks. Oscar’s Grind is another option, and its slow, grinding nature may appeal to fans of the D’Alembert.