Chance of at least one streak, by length
| Losses in a row | Probability | Bar | Drawdown |
|---|
How the odds are calculated
A losing streak of length k means at least k losses in a row. The calculator does not use a rule of thumb or a simulation: it computes the probability exactly with a Markov chain on your current streak length. After every trade you are on a run of 0, 1, 2 and so on up to k - 1 losses. A win sends you back to 0 and a loss moves you up one. The first time the run reaches k, that probability is set aside as "streak happened". After N trades, the set-aside total is the answer. With W as your win rate and q = 1 - W:
You can check it by hand on a tiny case. Over 5 trades at a 50% win rate there are 2^5 = 32 equally likely sequences. Exactly 8 contain 3 losses in a row (LLL then any 2 results: 4, WLLL then any 1: 2, any 1 then WLLL: 2), so the probability is 8 ÷ 32 = 25%. The chain gives the same 25%.
The longest streak to expect is the longest run that is more likely than not to happen at least once, the last length with a probability of 50% or more. Plan for it, and treat the next one or two lengths as realistic bad luck.
A worked example, step by step
A strategy wins 50% of the time, you take 100 trades, and you risk 1% of your balance per trade. The chain gives:
| Losses in a row | Chance over 100 trades | Drawdown at 1% |
|---|---|---|
| 5 | 81.01% | 1 - 0.99^5 = 4.90% |
| 6 | 54.61% | 1 - 0.99^6 = 5.85% |
| 7 | 31.75% | 1 - 0.99^7 = 6.79% |
| 8 | 17.02% | 1 - 0.99^8 = 7.73% |
| 10 | 4.41% | 1 - 0.99^10 = 9.56% |
6 is the last length above 50%, so 6 losses in a row is the streak to expect. The drawdown is 0.99 × 0.99 × 0.99 × 0.99 × 0.99 × 0.99 = 0.9415 of your balance left, a 5.85% drawdown. A 7 loss run still happens almost one time in three. Drop the win rate to 40% over the same 100 trades and the streak to expect grows to 7, with a 68.91% chance.
Streaks matter most where a hard limit sits close, such as a prop firm's daily or max loss. If 8 losses in a row at your size would breach the limit, a 17.02% chance of that inside 100 trades is a real risk. Pair this page with the risk of ruin calculator, see what a drawdown takes to win back with the drawdown recovery calculator, and see whole equity paths in the Monte Carlo trading simulator. Your win rate is only half the picture: the trade expectancy calculator tells you whether the strategy is worth the streaks, and the break-even win rate calculator shows how much room your win rate has.
How the RB Trading Pro Journal does this for you
The RB Trading Pro Journal works out your win rate, average R, expectancy and your longest losing streak from your real imported trades. You see the streak you have actually had next to the win rate behind it, so you can tell a normal run of losses from a strategy that has stopped working, and size so the next streak stays inside your limits.
Start free, no cardFAQ
Frequently asked questions
How many losing trades in a row is normal?
It depends on your win rate and how many trades you take. With a 50% win rate over 100 trades, at least one run of 6 losses in a row happens 54.61% of the time, so 6 is normal. At a 40% win rate over the same 100 trades, the streak to expect is 7, with a 68.91% chance.
How is the losing streak probability calculated?
The calculator tracks the probability of being on a current losing run of 0, 1, 2 and so on losses after every trade. A win resets the run to zero and a loss adds one. Once the run reaches the streak length, that probability is counted and set aside. It is an exact calculation, not a simulation or a rule of thumb.
How much drawdown does a losing streak cause?
If you risk a fixed percentage r of your current balance on each trade, k losses in a row leave you down 1 - (1 - r)^k. At 1% risk, 6 losses cost 5.85% and 10 losses cost 9.56%. If you size from your starting balance instead, the loss is simply k × r.
Does a losing streak mean my strategy has stopped working?
Not by itself. Streaks up to the expected length are normal variance for a strategy that still has an edge. A streak far longer than the calculator expects for your win rate and trade count is a reason to review your recent trades, your rules and the market conditions.
Do trades have to be independent for this to be accurate?
The math assumes every trade has the same win rate and does not depend on the one before. If your losses tend to cluster, for example in one type of market, real streaks can run longer than the calculator shows, so treat its numbers as a minimum.