Want to double your money gambling? A double your money calculator shows the best and worst ways to try. Turn £100 into £200 on European roulette with one bet on red and you’ve got a 48.65% chance. Try it with £5 bets instead and the free calculator above says 25.3%. With £1 bets it falls to under half a percent. The house edge eats more of your chance the more bets you make.
Double your money: bold play against small bets
Against a house edge, the best way to reach a target is to bet as much as you need in as few bets as possible, called bold play. Spreading it over many small bets gives the edge time to work. The gambler’s ruin formula gives the small-bet chance:
P(reach target) = (1 − r^i) ÷ (1 − r^N) r = chance of losing a bet ÷ chance of winning i = bankroll in bets, N = target in bets
| £100 to £200, red on European roulette | Chance |
|---|---|
| One £100 bet | 48.65% |
| £10 bets | 36.8% |
| £5 bets | 25.3% |
| £1 bets | 0.45% |
On a fair coin all of these would be 50%. The small house edge of 2.7% barely shows on one bet, but over hundreds of bets it decides the result.
What it doesn’t mean
Bold play gives the best chance of hitting a fixed target. It doesn’t make money: the average loss is the same 2.7% of everything you stake, and you lose the whole £100 more than half the time. And chasing a target after a loss is how sessions get out of hand. Pick the target and the stop before you start.
The chasing losses calculator shows what doubling up to win back a loss risks, and the risk of ruin calculator works out the chance of going broke over a long run. For the maths of doubling stakes, see the Martingale calculator.
Play for fun with money you won’t miss. If you’re spending more than you planned, BeGambleAware.org is free and confidential.