Systems library

D’Alembert Roulette System – Linear Progression Explained

A gentler up/down system that still depends on streak behaviour.

This guide explains how the system works step by step, why players like it, how it really behaves under streaks, and how it fits into the bigger picture of roulette math.

Use it alongside the Probability Calculator, EV Calculator and Losing Streak Calculator to see the numbers behind the ideas before risking real money.

1. What D’Alembert is trying to do

The D’Alembert system is a linear progression on even‑money bets. Instead of doubling after losses, you move your stake up or down by a single unit: +1 unit after a loss, −1 unit after a win (but never below 1 unit).

The idea is to keep stakes relatively close to your base bet while still “pressing” slightly into losses and easing off after wins. Volatility is lower than Martingale but higher than flat betting. Long losing stretches can still push stakes up and keep them elevated. The volatility & bankroll guide shows how those streaks play out in real numbers.

2. Basic D’Alembert rules

On an even‑money bet, standard D’Alembert rules are:

1

Choose a base unit (for example, $5) and start with a stake of 1 unit.
2

If you lose, increase your next stake by 1 unit (1 → 2 → 3 → 4...).
3

If you win, decrease your next stake by 1 unit, but not below 1 unit.
4

Continue until you reach a personal stop‑loss, stop‑win, or time limit for the session.

3. Example D’Alembert session

With a $5 base unit on an even‑money bet, a short sequence could look like:

Spin	Stake (units)	Stake ($)	Result	Next stake (units)	Cumulative P/L
1	1	$5	Lose	2	−$5
2	2	$10	Lose	3	−$15
3	3	$15	Win	2	0
4	2	$10	Win	1	+$10

In this friendly sequence, a couple of wins after losses leave you ahead by 2 units. But if the losing streak continued, your stake would creep to 4, 5, 6 units and so on, quietly increasing risk per spin.

4. Volatility, drawdowns & bankroll

D’Alembert’s volatility is much lower than Martingale’s but still higher than flat betting. Instead of explosive doubling, you experience a slow drift of stakes upward during bad runs and downward during good ones.

The main risks are:

Extended losing runs

Stakes can climb to multiples of your base unit, making each subsequent loss heavier.
Shallow recoveries

Climbing out of a deep drawdown can require many more wins than it took losses to get there.

The volatility & bankroll guide and Losing Streak Calculator together show how often those longer runs appear and how they stress a realistic session bankroll.

5. Pros, cons & realistic verdict

Aspect	Pros	Cons
Complexity	Very easy rules (+1/−1); minimal tracking required.	Still requires discipline to stop when limits are hit.
Volatility	Smoother ride than aggressive progressions.	Bad runs still push stakes and losses higher over time.
Psychology	Feels calmer and more manageable than Martingale.	Can encourage extended play because it “doesn’t feel too dangerous”.
Math reality	Decent structure for pacing small‑stakes entertainment.	Does not change the negative expectation shown in odds & edge.

D’Alembert can be used as a relatively gentle way to structure bets, but it should not be viewed as an edge. For long‑term expectations and misconceptions, see roulette system myths and the responsible gambling guide.