Martingale is a great win rate hiding a rare catastrophe
The appeal is obvious: if you double after each loss, the moment you finally win you recover every prior loss plus one base unit of profit. You win small, often. What the pitch never mentions is the shape of the loss. Because each step doubles and your bankroll is fixed, there is always a specific losing streak — usually shorter than traders guess — where the next required bet is larger than the money you have left. Hit it once and every accumulated small win is gone. You're not avoiding risk; you're trading a high win rate for a rare, total wipeout, which is exactly the trade a casino is happy to take from you.
Where your wall is
With a doubling multiplier, the total you've staked after n losses is base × (2ⁿ − 1). Your account survives the largest n where that sum still fits — the calculator marks it in red above. The cruel part is how little a bigger bankroll helps: because the requirement doubles each step, every extra loss you want to survive costs as much as everything before it combined. Ten times the bankroll buys you barely three more losing trades. Halving the base bet buys you exactly one. There is no bankroll large enough to make martingale safe, only large enough to hide the wall for longer.
The probability of ruin is not zero — it compounds
A losing streak long enough to break you is unlikely on any single run. But you don't trade once. Over a session of many trades, and over many sessions, the chance that such a streak appears at least once climbs steadily toward certainty. The calculator estimates that odds for your session from your per-trade loss probability. Crypto makes it worse than the coin-flip math: leveraged trades correlate, volatility clusters, and funding plus fees quietly bleed the edge, so real losing streaks run longer and cost more than a fair coin would suggest. Sanity-check the same account against the risk of ruin calculator and your realistic longest losing streak.
Anti-martingale flips the risk
Switch the toggle to anti-martingale and the picture inverts. Now you double after wins and reset after losses. A cold streak just costs a series of small base bets — bounded, survivable — while a hot streak compounds. You give up the comforting high win rate, but you remove the tail that ends accounts. This is why most durable risk frameworks lean anti-martingale: scale up when the market is paying you, cut back when it isn't. Size every entry deliberately with the position size calculator instead of letting a doubling rule decide for you.
How to use it
1. Enter your bankroll and the base (first) position size.
2. Set the multiplier (2 = classic doubling) and your realistic per-trade loss probability.
3. Read the streak your account survives, the ladder of bet sizes, and the estimated chance of ruin over your session. If that number isn't comfortably near zero, the strategy is quietly negative for you.
FAQ
Is a smaller base bet safer? Barely. Each halving of the base bet buys just one extra survivable loss, because every rung doubles. It moves the wall, it never removes it.
What multiplier is "safe"? None guarantees safety, but a multiplier below 2 (partial martingale) grows the ladder more slowly and pushes the wall out. It also means a win no longer fully recovers prior losses, which defeats the original point.
Does this apply to grid and DCA bots? Grid and averaging-down bots are martingale in disguise — they add size as price moves against them. The same wall exists. Model your worst-case drawdown before running one, not after.