The Martingale betting strategy says double your stake after every loss, so one win gets everything back plus your first stake. It fails because losing runs happen more often than people expect and the stakes grow faster than any bankroll.
How it's meant to work
You bet £1 at evens. Lose, and you bet £2. Lose again, £4. Then £8. Whenever you win, you're £1 up on the whole run and you go back to £1.
It sounds safe because you only need one win. The problem is the cost of waiting for it.
How fast the stakes grow
| Losses in a row | Next stake | Lost so far |
|---|---|---|
| 3 | £8 | £7 |
| 5 | £32 | £31 |
| 7 | £128 | £127 |
| 10 | £1,024 | £1,023 |
| 12 | £4,096 | £4,095 |
After ten losses you're staking over £1,000 to win back £1. And bookmakers set maximum stakes, so you may not be allowed to place the next bet at all.
Losing runs aren't rare
Ten losses in a row on a coin flip sounds unlikely. On any one run it's about 1 in 1,024. But over 1,000 bets, the chance of hitting at least one run of ten or more losses somewhere is about 39%.
It gets worse at real bookmaker prices. Many "coin flip" markets are priced around 10/11, not evens. At 10/11 a win after four or more losses in a row doesn't even get you back to level. The bookmaker's margin eats the £1 you were chasing.
Run the Martingale simulator
This simulator runs the Martingale thousands of times with your numbers. Change the bankroll, the odds and the true chance of winning and see what happens.
Doubling doesn't change the expected result
The Martingale doesn't change your expected result. It swaps lots of small wins for the occasional huge loss. At bookmaker prices the expected result is a loss, and doubling makes that loss arrive in bigger chunks.
Questions people ask
Does the Martingale work in betting?
No. It can't turn bets that lose on average into bets that win on average. It only changes the shape of your results: frequent small wins and rare big losses.
What about the reverse Martingale?
You double after wins instead of losses. It has the opposite shape, frequent small losses and rare big wins, but the same problem. It doesn't change the expected result either.
Can a big bankroll make it work?
A bigger bankroll makes the big loss rarer, not smaller. When it comes, it costs more. Bookmaker stake limits also stop the doubling long before most bankrolls run out.