Free tool · Monte Carlo

Losing Streak Calculator — Probability of X Losses in a Row

Every strategy that loses sometimes will lose several times in a row. This losing streak probability calculator runs thousands of Monte Carlo samples of your win rate to show how likely consecutive losses really are — more accurately than the textbook formula.

Your trading

Win rate (%) 55%

Trades in the sample

Simulation

Analyze streak length K 5

Simulations

P(losing streak ≥ K)

—

chance of at least 5 losses in a row within 100 trades

Expected longest losing streak

—

average across all simulations

Longest observed streak

—

worst single simulation

P(win streak ≥ K)

—

the upside of the same math

Know your real win rate first

The ReziFX extension captures your planned trades straight from the TradingView position tool into a journal — win rate, average R and drawdown are computed automatically, so this calculator runs on your real numbers instead of guesses.

Try ReziFX free Monte Carlo simulator

Streak probabilities for your inputs (K = 3 … 12)

Streak length K	P(losing streak ≥ K)	Roughly one in …

Why the textbook formula overestimates

Most articles quote the shortcut P ≈ 1 − (1 − p^K)^n−K+1, where p is the per-trade loss probability, n the number of trades and K the streak length. It looks rigorous — and it is systematically wrong, because it treats the n−K+1 overlapping windows of K trades as independent events. They are not: neighbouring windows share almost all of their trades.

The error is not small. At a 55% win rate, n = 100 trades and K = 5, the exact probability of at least one 5-loss streak is 64.7%. The shortcut formula returns 83.3% — 18.6 percentage points too high. That is the difference between "happens in about two of three samples" and "near certainty", and it grows with the sample size.

Exact streak probability requires a Markov-chain recursion over run states, which no pocket formula reproduces. This tool takes the other reliable route: it simulates thousands of full trade sequences and counts how often streaks of each length actually occur. With 5,000+ simulations the estimate settles within a fraction of a percentage point of the exact value — without the flawed independence assumption.

What the result should change is not your entry signal but your sizing: if a streak of 7 is well within normal variance for your win rate, your risk per trade must survive 7 consecutive losses without forcing you to stop trading. That is exactly the sequence-of-returns math the risk of ruin calculator builds on.

Frequently asked

How many losses in a row should I expect?

It depends on your win rate and how many trades you take. At a 55% win rate over 100 trades, the longest losing streak typically lands around five to six trades, and a streak of at least 5 happens in roughly two out of three 100-trade samples. Run the simulation with your own numbers — the distribution is wider than most traders expect.

Does a losing streak mean my strategy is broken?

Not by itself. Streaks of losses are a statistical certainty for any strategy that loses sometimes. Compare your observed streak against the simulated distribution for your win rate and sample size: if streaks of that length appear in a meaningful share of simulations, the streak is consistent with normal variance. Only a streak far outside the simulated range is evidence that something may have changed.

How does win rate change streak odds?

Non-linearly. The probability of a K-loss streak scales with the loss probability raised to the power K, so a few percentage points of win rate compound over the length of the streak. Dropping from a 60% to a 40% win rate makes long losing streaks dramatically more likely, not just somewhat more likely. The table above shows the full K = 3 to 12 range for your inputs.

Why use simulation instead of a formula?

Exact streak probability requires Markov-chain style recursion; the widely quoted closed-form shortcut 1 − (1 − p^K)^(n−K+1) treats overlapping windows as independent and overestimates badly. At a 55% win rate, 100 trades and K = 5, the true probability is about 64.7% while the formula gives 83.3% — 18.6 percentage points too high. Monte Carlo simulation converges on the true value without the flawed independence assumption.

Educational tool. Not financial advice — trading involves substantial risk of loss.