Losing Streak Probability Calculator
How likely is a run of consecutive losing trades, and how long a streak should I plan for?
Losing streak odds
Exact probability for independent trades
Probability of the streak
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Chance of a losing streak by length
Streak table
More trades, more streaks
Methodology
Important: Estimation Only
This calculator provides mathematical projections based on the assumptions and historical/backtest statistics entered by the user. It is not a guarantee or prediction of future trading results. Actual EA performance may vary significantly due to market conditions, volatility, liquidity, spread, slippage, execution quality, commission, swap, news events, market sentiment, changes in market regime, broker conditions and differences between backtest, forward-test and live trading.
Past performance and backtest results do not guarantee future results.
How losing streak probability is calculated
A common shortcut is to raise the loss rate to the power of the streak length. That gives the chance of a streak starting on one particular trade, not the chance of seeing one somewhere in a trading year, which is far higher.
This calculator follows every trade in sequence and keeps the exact probability of each possible current losing run. After the last trade, one minus the probability that no run ever reached the chosen length is the answer.
P(run ≥ k in n trades) = 1 − P(no run of k losses in n trades)
Worked example
With a 55% win rate, the chance that any single set of 8 trades are all losses is 0.45⁸ ≈ 0.17%. Over 500 trades, the chance of at least one run of 8 or more losses is about 37%.
At 1% risk of the current balance, 8 straight losses is a drawdown of 1 − 0.99⁸ ≈ 7.7%. Planning for the 95% streak length rather than the typical one keeps risk sized for the bad runs, not the average ones.
Frequently asked questions
How likely is a losing streak of 10 trades?
It depends on the win rate and on how many trades you take. With a 50% win rate, a run of 10 or more losses somewhere in 1,000 trades has about a 38.5% probability. With a 60% win rate it drops to about 6.1%.
How is the probability calculated?
The calculator tracks the exact probability of every possible current losing run, trade by trade, for the number of trades you enter. The result is exact for independent trades with a constant win rate, not an approximation.
What streak length should I plan for?
The calculator reports the streak length that 95% of trade sequences of your length stay within. Sizing risk so that this streak causes a drawdown you can tolerate is a common way to set risk per trade.
Why do long streaks happen even with a good win rate?
Over hundreds of trades there are many starting points for a streak, so rare runs become likely. A 60% win rate still produces a run of 6 or more losses in 500 trades about 71% of the time.