Why a winning system still gives you brutal streaks
Every independent trade is a coin flip weighted by your edge. Flip a 45%-tails coin two hundred times and you will see long tails runs — that's not bad luck, it's the expected behaviour of randomness. The expected longest losing streak over N trades is roughly log(N) ÷ log(1 ÷ loss-rate). At a 55% win rate over 200 trades that's about 6–7 losses in a row; drop to a 45% win rate (still profitable with good reward:risk) and it climbs past 9. The streak is baked into the strategy the moment you know its win rate — the only question is when it shows up.
The real damage is the reaction, not the streak
A losing streak rarely blows an account on its own. What blows it is the response: doubling size to "win it back", abandoning a working system at the exact bottom of a normal drawdown, or revenge-trading the next setup. If you've already seen — before it happens — that a 7-loss run is ordinary for your strategy, you're far less likely to panic when it arrives. That's the entire point of this simulator: turn the streak from a shock into an expected weather event. See the revenge trading calculator for what the panic response actually costs.
Risk per trade is the dial that matters
The same streak is survivable or fatal depending on size. Losses compound on a shrinking balance, so a 7-loss run costs 1 − (1 − risk)^7. At 2% per trade that's about 13% — annoying, fully recoverable. At 5% it's 30%, which needs a 43% gain just to get back to flat. At 10% it's over 52%, and now you're in the hole where the math of ruin takes over. Pick a risk-per-trade small enough that your expected worst streak is merely uncomfortable, never terminal, then size every position with the position size calculator.
How to use it
1. Enter your strategy's win rate and how many trades you're modelling.
2. Enter your risk per trade and the streak length you want the odds for.
3. Read the expected longest streak, then the table — does the drawdown from your likely worst streak fit inside what you can stomach?
FAQ
Does this assume independent trades? Yes — each trade is treated as independent with a fixed win probability. Real trading has streaks of correlation (regime changes, tilt), which makes actual runs slightly worse than the model, so treat these numbers as the optimistic floor.
What win rate should I use? Your real, fee-adjusted historical win rate over a meaningful sample — not your best month. If you don't have one, model a range (45%, 55%, 65%) to see how sensitive your streaks are.
Is a high win rate safer? For streaks, yes — but win rate alone doesn't make a system profitable; reward:risk matters just as much. A 40% system with 3:1 winners beats a 60% system with 1:2 winners. Check both with the risk/reward calculator.