D'Alembert vs Flat Betting

Which roulette betting strategy is right for you? Compare these two popular systems side-by-side.

D'Alembert Strategy

Increase bet by one unit after a loss, decrease by one after a win.

moderatesimplenegative progression

Flat Betting Strategy

Bet the same amount on every spin regardless of wins or losses.

conservativesimpleflat progression

10,000 Simulated Sessions Each: D'Alembert vs Flat Betting

We ran both systems through 10,000 simulated sessions on a European wheel under identical conditions: $1,000 bankroll, stopping at $1,500 (win), $500 (loss), or 500 spins.

Measured over 10,000 sessions	D'Alembert	Flat Betting
Sessions ended in profit	36.6%	25.7%
Average session result	−$155	−$132
Average spins per session	163	490
Average worst drawdown	−$413	−$244
Best single session	$565	$500
Worst single session	−$610	−$500

In this run, D'Alembert ended more sessions in profit, while Flat Betting lost less on average — a classic trade-off between win frequency and loss size. Neither beat the house edge.

How D'Alembert sessions ended

Losing sessionsWinning sessions

Lost over $800

Lost $400–$800

63.4%

Lost $100–$400

Lost up to $100

Won up to $100

Won $100–$400

Won $400–$800

36.6%

Won over $800

How Flat Betting sessions ended

Losing sessionsWinning sessions

Lost over $800

Lost $400–$800

11.9%

Lost $100–$400

42.7%

Lost up to $100

17%

Won up to $100

12.4%

Won $100–$400

15%

Won $400–$800

1.1%

Won over $800

Methodology: fixed-seed runs from our open simulation engine, using the same settings as the strategy guides and interactive simulators — the numbers here match each system's guide page and can be reproduced there. Both systems lose on average because no betting progression changes the house edge; the comparison shows how differently they get there.