Bankroll
Why Doubling Down Can Be Dangerous
The math behind doubling your bet after every loss (the Martingale), and why it can wipe out a bankroll.
By Jared Narz · · 2 min read
"Double your bet after every loss and the first win gets it all back." This idea, often called the Martingale, sounds foolproof. The math says otherwise.
How it works
Start with 1 unit at even money (+100). After a loss, double the stake. When you win, you recover all previous losses plus 1 unit, then start over.
Illustrative example: a losing streak
| Bet # | Stake | Total lost so far |
|---|---|---|
| 1 | 1u | 1u |
| 2 | 2u | 3u |
| 3 | 4u | 7u |
| 4 | 8u | 15u |
| 5 | 16u | 31u |
| 6 | 32u | — |
After five straight losses you need to risk 32 units to win back 31 units and net 1 unit. Stakes grow exponentially while the reward stays tiny.
Why it fails
- Losing streaks happen. Even on a true 50/50 bet, any particular run of five bets has a 1-in-32 chance (0.5⁵) of losing all five. Over hundreds of bets, long streaks are expected.
- Bankrolls and limits are finite. Eventually you can't place the next bet, or the platform won't accept it.
- The vig makes it worse. At -110 a win pays less than the stake, so after four or more straight losses the doubled bet no longer even covers what you've lost. Illustrative: down 15u, a 16u win at -110 pays about 14.5u.
- It doesn't change expected value. Doubling changes how losses are distributed, not whether a bet is +EV. A -EV bet is still -EV at any stake.
A better approach
Use consistent unit sizing, focus on finding value, and accept that losing streaks are part of betting. If you feel the urge to double up to get even, that's a signal to step away. See Avoiding Chasing Losses.
Examples are illustrative and use hypothetical numbers. This article is educational content, not financial advice or a guarantee of results. 21+. Bet responsibly.