Trading Losing Streak Calculator
Strategy assumptions
What the sequence risk looks like
The common probability mistake
If a strategy wins 60% of trades, its loss probability is 40%. Five particular trades all losing has probability 0.4⁵, or 1.024%.
But a 100-trade sample gives a five-loss streak many chances to occur. Those candidate windows overlap, so multiplying 1.024% by the number of windows is not a valid probability calculation. The exact finite-state calculation gives about 45.91% for at least one five-loss streak somewhere in 100 independent trades.
How the exact calculation works
The algorithm tracks the probability that no target streak has occurred yet while the current sequence ends with 0, 1, 2, and so on trailing losses. A win resets the trailing-loss state to zero. A loss advances it by one. Probability that would advance into the target streak is removed from the surviving states.
After all trades, one minus the surviving probability is the exact chance that the target losing streak occurred at least once. This is deterministic dynamic programming, not Monte Carlo sampling.
Win rate is not enough to describe a trading system
This tool assumes independent trades with one constant win probability. Real strategies can cluster losses because market regimes, volatility, signal overlap, common exposures, execution failures, and model drift create dependence. A backtest can also overstate the win rate through overfitting or leakage.
The drawdown calculation assumes each losing trade loses the entered fraction of then-current equity. It does not model variable loss size, partial wins, commissions, slippage, gaps, leverage, correlated positions, or changing position size rules.
Use it as a sequence-risk stress test, not as proof that a strategy is safe. The algorithmic trading guide covers the broader system. The transaction-cost tool stress-tests execution drag, while futures position sizing handles trade-level contract sizing.
Reusable probability grid
The published sensitivity data covers 40%, 50%, 60%, and 70% win rates across 50, 100, and 250 trades for losing streaks of 3, 5, and 8 trades. Every value is generated from the same exact state-transition calculation used above.