Risk of ruin calculator
A positive edge does not protect you if you risk too much per trade. This estimates the odds that a losing run ends the account before the edge has time to work.
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Risk of ruin is driven far more by risk per trade than by win rate. A 55% strategy at 1.5:1 has a healthy edge. But risking 10% per trade still ruins a meaningful share of accounts, while the same strategy at 1% per trade almost never does.
Key takeaways
- You can have a genuine edge and still go broke. Position size decides whether the edge gets the chance to play out.
- Halving your risk per trade cuts risk of ruin by much more than half. The relationship is exponential, not linear.
- Long losing streaks are normal. At a 55% win rate, an eight-loss run appears roughly once every 250 trades.
- The estimate assumes your win rate is stable. In reality it varies with market regime, which makes the real risk higher than any model shows.
How this is estimated
Closed-form risk-of-ruin formulas assume a 1:1 payoff, which almost no strategy has. Instead of forcing that assumption, this tool simulates: 20,000 independent accounts, each trading up to 1,000 times, with risk recalculated off the live balance every trade. It counts how many hit the drawdown you defined as ruin.
Because it is a simulation, the result moves by a few tenths of a percent between runs. That is honest. The underlying quantity is a probability, not a constant, and a spuriously stable figure would imply more precision than exists.
Two inputs deserve care. Win rate should come from your own record over a meaningful sample, not from a strategy's advertising. Reward-to-risk should be the average realised ratio, which is usually lower than the planned one because winners get cut early and losers occasionally slip past the stop.
Losing streaks are normal
The intuition that a 60% win rate means you rarely lose several in a row is wrong. Over 200 trades at a 60% win rate, a run of six consecutive losses is more likely than not.
| Win rate | Longest losing run expected in 200 trades |
|---|---|
| 70% | 4–5 trades |
| 60% | 6–7 trades |
| 50% | 7–8 trades |
| 40% | 10–11 trades |
Your risk per trade has to be small enough that the expected streak is an inconvenience rather than an emergency. At 1% risk, a seven-loss run costs about 6.8%. At 5%, it costs 30%, and the temptation to abandon the strategy at exactly the wrong moment becomes overwhelming.
This is also why win rate on its own is a poor way to judge a signal service. A high headline figure with a poor reward-to-risk ratio can have a negative expectancy. MarketPro's editorial policy explains why we publish entry, stop and targets on every signal rather than leading with a win-rate number.
The same calculators are inside the MarketPro app
MarketPro ships position size, pip value, margin, profit, risk-to-reward and compounding calculators alongside the signal feed, so you can size a trade on the same screen you read it on. Download free. Vetted free signals every week, no card needed.
Risk of ruin calculator: questions
What is a safe risk of ruin?
Can I have a positive expectancy and still go broke?
What win rate do I need to be profitable?
Size the trade, then take the trade
MarketPro publishes every signal with an explicit entry, stop and take-profit levels, which is what makes these calculations possible before you click. Start with the free weekly signals.
Not investment advice. Past performance is not indicative of future results.