Losing Streak Calculator

Estimate how often a strategy can hit a run of consecutive losses, even when the long-run win rate looks reasonable.

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

Win rate (%)

Number of trades

Loss streak to test

P(at least one ≥k loss run) = 1 − P(no k-run), using exact dynamic programming

Consecutive-loss risk

Loss probability per trade—

One isolated k-loss streak—

At least one k-loss run—

Expected longest loss run—

Enter a sample size and the streak length you want to stress.

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.

How does the calculator avoid random simulation?

It uses exact dynamic programming for the probability of no k-loss run, then takes the complement. There is no random sampling, so the same inputs always produce the same output.

What does expected longest loss streak mean?

It is the average longest loss run implied by the model over many sequences of the same length and loss probability. It is not the maximum possible streak.

Should I use win rate from backtests or live trades?

Use the sample you trust most. A backtest may overfit, while live results may be small. The calculator only transforms the win rate you enter.

Can a profitable system still have long losing streaks?

Yes. Profitability comes from the mix of win rate and payoff. A positive-expectancy system can still have uncomfortable loss runs, which is why position sizing matters.

Related calculators

Funded-account checks

Use these three pages as a simple path: understand the rules, stress a scenario, then track consistency before a payout.

1Understand the ruleCompare challenge types, drawdown floors and payout logic.2Run a breach scenarioModel intraday vs end-of-day trailing drawdown before sizing a trade.3Track consistencyCheck whether one big day is blocking payout eligibility.

Information tool only. Every result is deterministic arithmetic (for the simulator, a probability estimate) from the numbers you enter. The calculators run in your browser with no account connection and nothing stored; the pairs scanner uses delayed, cached market data (daily figures, refreshed once a day), not a live feed. This is not investment, trading, tax, or financial advice — verify against your own broker or prop firm before acting.

Disclosure. Some outbound links may be affiliate or partner links; they never change how a tool computes.

Position Math · updated 2026-07-04 · all calculators
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Information tool only — not investment, trading, tax, or financial advice. All computation runs in your browser.