How to use the losing streak calculator
- Enter your win rate as the percentage of your trades that finish in profit. Decide first how you count break-even trades; counting them as losses is the cautious choice.
- Enter the number of trades the stretch covers, from 1 to 1,000. A month of trading, a quarter or a year are all sensible choices.
- Enter the streak length you want the odds for: the number of losing trades in a row.
The large figure is the chance that at least one run of that many losses appears somewhere in those trades. Below it you get how often that happens (once in how many stretches), the longest streak to expect on average, the median longest streak and the streak that only one stretch in twenty reaches. Two charts show how the odds change with the streak length and how the longest streak grows with the number of trades.
The losing streak formula
For one fixed starting point, the chance that the next N trades all lose is simple:
chance of N losses starting now = q^N where q = 1 − win rate
At a 45% win rate that is 0.55 to the power of 10, or 0.25%, for ten losses. But that is one starting point. A streak can begin at any trade, and the real question is whether it appears at least once somewhere in T trades. That has no one-line formula, so the calculator computes it exactly by dynamic programming on the current run of losses:
state j = chance that the run of losses right now has length j (j = 0 to N − 1)
after each trade:
new state 0 = (sum of all states) × win rate
new state j + 1 = state j × q for j + 1 < N
streak reached = state N − 1 × q (added to the answer, taken out of play)
chance of at least one streak = total reached after T trades
N is the streak length, T the number of trades and q the loss rate. The method is exact for independent trades. There is no simulation, so the same inputs always give the same answer, to the last digit.
The longest-streak figures come from the same idea applied to every streak length at once. The chance that the longest streak is n or more, added up over all n, is the expected longest streak.
A mental estimate also works. The expected number of streaks of N losses is about T × win rate × q^N, and the chance of at least one is roughly 1 − e^(−that number). At 45%, 200 trades and N = 8 the estimate is 0.75 streaks and 52.9%, a tenth of a point from the exact answer.
Worked example
A trader wins 45% of trades, so 55% lose. How likely is a run of 8 or more losses in 200 trades?
These are the numbers the calculator opens with. The column chart shows the rest of the picture: 7 or more losses in a row has a 75.6% chance, 9 or more 33.5%, 10 or more 19.9%, 12 or more 6.4% and 15 or more 1.1%.
The streak is more likely than not, and it sits at the middle of the distribution, not in its tail. A trader who meets eight losses in a row after 200 trades has had an ordinary run of luck at this win rate.
Why losing streaks are normal
People expect random sequences to alternate: win, loss, win, loss. Real ones do not. They clump, and a run of five or six of the same result is common. Because it looks like a pattern, a streak feels like a message that something has changed, when it is often just the arithmetic of 55% losing trades.
The line chart shows how much room the streak has to grow. At a 45% win rate the expected longest streak is 6.9 losses in 100 trades, 8.0 in 200 and 10.7 in 1,000. Each doubling of the number of trades adds about 1.2 to it. The more you trade, the longer the worst run you will meet, with no change in skill.
A streak is also how a drawdown starts. Several losses in a row take equity down faster than the average trade brings it back, and that is when rule-breaking often begins. Frustration after a run of losses is called tilt, and it turns a normal streak into an expensive one. The guide to how to stop revenge trading covers the habit that follows.
How win rate and trade count change the streak
Win rate is the strongest lever. This table holds the trades at 200 and the streak at 8, and changes only the win rate.
A strategy that wins 35% of the time meets eight losses in a row in about nine runs out of ten. That is a feature of the style, not a fault: trend-following systems often win less than half of their trades and make it back with larger winners.
A high win rate shortens streaks without removing them. At 70% the expected longest streak in 200 trades is about 4, and a run of 5 losses still happens in roughly 29% of runs.
Planning for the streak you will meet
Plan for the bad-luck streak, not the average one. The calculator gives both: at 45% over 200 trades the expected longest is 8, but the streak that one run in twenty reaches is 12.
Then turn the streak into money. With 1% of equity at risk on every trade, 12 losses in a row cost about 11.4% of the account (1 − 0.99^12). At 2% risk the same streak costs about 21.5%. Whether you can sit through that, financially and emotionally, is worth settling before the streak arrives. The risk of ruin calculator shows how a streak interacts with a loss limit.
Rules made during a streak are made on tilt, so write them in advance: a daily loss limit, a stop after a set number of losses in a row, a reduced size until two trades are back in profit. None of this changes the odds. It limits what a normal streak can cost you.
Common losing streak mistakes
- Treating a streak as proof the system broke. Eight losses in a row at a 45% win rate is the expected outcome of 200 trades, not evidence of change.
- Using the win rate you hope for. Take it from your journal. A win rate of 55% that is really 45% turns a 16.5% chance of an 8-loss run in 200 trades into a 53% one.
- Planning for the average streak. Half of all runs are worse than the expected longest streak. Plan for the one-in-twenty case.
- Believing a win is due. Trades are independent in the maths, and the next trade has the same odds after eight losses as after none. This is the gambler's fallacy.
- Raising size to win it back. A larger size after a streak means the next loss cuts deeper, and it is the usual start of a blow-up.
- Counting break-even trades inconsistently. Decide once whether they are losses and keep the rule.
- Trusting a win rate from a handful of trades. The win rate itself carries uncertainty, which the win rate confidence calculator puts a range on.
What the calculator does not know
It assumes every trade is independent and wins with the same probability. In real markets losses can cluster: a strategy built for trends loses repeatedly in a choppy market, and the win rate changes with conditions. Real streaks can therefore run longer than the figures here.
It counts losses, not money. Eight small losses and eight full-size losses are the same streak to the calculator and very different to your account. It also takes your win rate as exact, when a win rate measured on a limited sample is itself a range. Nothing here is investment advice.
Frequently asked questions
How do you calculate the probability of a losing streak?
Work out the chance that at least one run of N losses appears in T trades, which depends on the loss rate, N and T. The calculator does this exactly by tracking the length of the current run of losses after every trade. For a single starting point the chance is the loss rate raised to the power N, but a streak can start at any trade, which is why the longer calculation is needed.
What is the probability of 10 losses in a row?
It depends on the win rate and how many trades you look at. At a 45% win rate the chance that the next 10 trades all lose is 0.25%, but across 200 trades the chance of a 10-loss run somewhere is 19.9%, about one in five. Over 1,000 trades it rises to 68.2%.
How many losses in a row is normal?
At a 45% win rate, 8 losses in a row is normal in 200 trades: it is the expected longest streak, and it happens in 53% of runs. At 50% the expected longest streak in 200 trades is 7, and at 70% it is about 4. Enter your own win rate and trade count to see what is normal for you.
What is the longest losing streak to expect in 100 trades?
At a 50% win rate the expected longest streak in 100 trades is 6, and one run in twenty reaches 9. At 45% the expected figure is 6.9. Use the line chart to read the figure for any number of trades up to 1,000.
Does a high win rate protect you from losing streaks?
It shortens them but does not remove them. At a 70% win rate the expected longest streak in 200 trades is about 4 losses, and 5 in a row still happens in roughly 29% of runs. Streak length depends on the loss rate, and even a 30% loss rate produces runs.
Does a losing streak mean my strategy has stopped working?
Not by itself. A streak of the length the calculator calls normal says nothing about the system. A streak far past the one-in-twenty figure, or a drop in win rate that a larger sample confirms, is a reason to review the trades.
Is a win more likely after a losing streak?
No. If trades are independent, the chance of a win is the same after eight losses as after none, and expecting a win to be due is the gambler's fallacy. A very long streak is unlikely to begin with, but the next trade does not know about the last ones.
How should I handle a losing streak?
Follow rules you wrote before it started: a daily loss limit, a stop after a set number of losses and a reduced size until you are trading well again. Then review the trades for rule breaks, and watch for the signs that the streak is changing how you trade, such as bigger size or trades outside your plan.
Is this losing streak calculator exact or a simulation?
It is exact. The probabilities are computed with dynamic programming, not estimated from random runs, so they are the same every time you enter the same numbers. They are exact only for the model, which assumes independent trades with a fixed win rate.
How does the number of trades change the longest streak?
More trades give more chances for a long run, and the longest streak grows slowly. At 45% it rises from 6.9 at 100 trades to 8.0 at 200 and 10.7 at 1,000, about 1.2 more losses for each doubling.