Calculators › Trading
Losing Streak Calculator
The losing streak calculator estimates how often a run of consecutive losses shows up across a sample of trades — the streaks that arrive even when the long-run win rate looks reasonable. Browser-only, nothing stored.
A losing-streak calculator estimates how likely it is to see at least one run of k or more consecutive losses inside N trades by using an exact no-k-run dynamic program, then sums those probabilities to estimate the expected longest loss run.
Streak inputs
Consecutive-loss risk
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How it works
What this calculator does
It estimates the probability of seeing at least one run of k or more consecutive losses inside N trades. This is different from the isolated probability of exactly k losses in a row, because a long sample gives the streak many chances to appear.
The formulas
q = 1 − p, where p is win rate.
q^k is the probability of one specific run of k losses.
For the full sample, the engine computes P(no k-loss run) with exact dynamic programming. It tracks the current trailing loss count from 0 to k−1; a win resets the state to 0, and a loss moves one state higher. The final probability is 1 − P(no k-loss run).
The expected longest loss streak is Σ P(at least one k-loss run) over all possible streak lengths.
Worked example
With a 50% win rate, the chance of one specific 5-loss sequence is only 0.5^5 = 3.125%. Across 100 trades, however, there are many overlapping places where a 5-loss run can occur, so the at-least-once probability is about 81.01%.
What it deliberately does not do
It assumes independent trades with the same win probability. Real strategies cluster wins and losses, especially around market regimes. If your losses are correlated, this model can understate streak risk.
Frequently asked questions
Why is the at-least-once losing-streak probability higher than q^k?
q^k is the chance of one specific streak starting at one specific point. Over many trades the streak can start in many places, so the chance of seeing it at least once is much higher.