d'Alembert roulette strategy tested: 10,000 simulated sessions on red
Does the d'Alembert system work in roulette? Not against the house edge, which no staking plan changes. Over 10,000 simulated sessions of d'Alembert on red on a European wheel, the average result was -$1,972 a session, against an exact expected loss of $2,007; 31.4% of sessions finished ahead and 62.3% went bust.
Add one unit after a loss, take one away after a win. 10,000 sessions of 500 spins, seed 2026. Tags: negative progression
mean -$1,972 ± $83.47 per session · P(ahead) 31.4% · bust 62.3%
The numbers on this page come from a real run of 10,000 sessions of up to 500 spins, $5,000 bankroll, $25 unit, European wheel, saved in the spinner gallery. They are exactly what spinner’s Analyze screen shows for it, with 95% intervals.
Open this run in spinner: charts and every sessionTest your own system
How the stakes move
One unit more after a loss, one less after a win (never below one); capped at 20 units.
One bet each spin, on red, pays 1 to 1. It starts at 1 unit ($25). After a loss the stake goes up by 1 unit ($25); after a win it comes down by 1 unit ($25), never below the start.
There are 20 levels, up to 20 units ($500); a loss at the top level means it stays at the top stake.
Stakes, level by level: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 units ($25 to $500).
The simulation
- Wheel
- European (single zero, 37 pockets)
- Bankroll per session
- $5,000
- Unit (base bet)
- $25
- Spins per session (at most)
- 500
- Sessions simulated
- 10,000
- Pace
- 40 spins an hour
- Table maximum (outside bets)
- $5,000
- Seed
- 2026
Results
| Measure | Value | 95% interval |
|---|---|---|
| Mean net result per session | -$1,972-$2,056 to -$1,889 | -$2,056 to -$1,889 |
| Median net result per session | -$5,000-$5,000 to -$5,000 | -$5,000 to -$5,000 |
| 10th / 90th percentile of the net result | -$5,000 / +$5,350 | |
| Best / worst session | +$6,975 / -$5,000 | |
| Spread (SD) per session | $4,259 | |
| Chance of finishing ahead | 31.4%30.5% to 32.3% | 30.5% to 32.3% |
| Chance of going bust (losing the whole bankroll) | 62.3%61.4% to 63.3% | 61.4% to 63.3% |
| Chance of playing all 500 spins | 37.7%36.7% to 38.6% | 36.7% to 38.6% |
| Expected loss per sessionexact, from the odds of every bet placed | $2,007 | |
| Realized loss per session | $1,972$1,889 to $2,056 | $1,889 to $2,056 |
| Expected loss per hourat 40 spins an hour | $241.52 | |
| House edge: realized vs exactloss as a share of everything wagered | 2.7% vs 2.7%2.5% to 2.8% | 2.5% to 2.8% |
| Mean amount wagered per session | $74,259 | |
| Run luck (z)how far the whole run is from the odds; within ±2 is ordinary | +0.72 |
6,232 bets were rejected (6,232 not enough bankroll) and not played, in 62.3% of sessions: the strategy asked for a stake the remaining bankroll could not cover.
11,480 bets were adjusted to fit the table (clamped, reduced or rounded).
Against Flat on red, run with the same seed and setup: mean result -$1,972 vs -$342.36 a session, finished ahead 31.4% vs 25.9%, went bust 62.3% vs 0.0%, and $74,259 vs $12,500 wagered in an average session.
Risk: drawdowns and bet size
| Measure | Value | 95% interval |
|---|---|---|
| Mean max drawdown (largest fall from a peak) | $5,802$5,769 to $5,835 | $5,769 to $5,835 |
| Median max drawdown | $5,825$5,775 to $5,850 | $5,775 to $5,850 |
| 90th / 99th percentile drawdown | $7,900 / $9,475 | |
| Chance of a drawdown of at least half the bankroll ($2,500) | 95.1%94.7% to 95.5% | 94.7% to 95.5% |
| Mean largest amount on the table | $488.05$487.32 to $488.78 | $487.32 to $488.78 |
| 99th percentile largest amount on the table | $500 | |
| Largest amount on the table in any session | $500 | |
| Chance of reaching the table maximum ($5,000) | 0.0%0.0% to 0.0% | 0.0% to 0.0% |
| Mean session lengthhalf of the sessions had ended by spin 351 | 332 spins |
Why no progression changes the house edge
Every roulette bet pays a little less than its true odds, because of the zero. On the European wheel used here every bet carries the same edge: 2.7% of each dollar wagered, in every run on this site, whatever the system. A betting system changes only how much you bet and when. Each spin is independent of the ones before it, so no sequence of stakes can change the edge: the expected loss is always the edge times the total amount wagered. In this run an average session wagered $74,259 in total, and the realized loss came to 2.7% of everything wagered, against the exact 2.7%.
What a system does change is the size of the bets, and with it the total wagered and the shape of the results. Raising the stake after a loss puts more money through the wheel, so the expected loss grows with it, and the risk piles up in the long losing streaks that the progression cannot afford. Compare the amount wagered, the bust rate and the drawdowns of each system in the table on the strategies page.