Risk of Ruin Calculator: Will Your Risk Setting Survive?
Position sizing is not about how much you can make, it is about whether a normal losing run can end you. Enter your numbers and see the probability, simulated over thousands of runs.
Risk of ruin is the probability that a losing run takes your account down to the level you call done. It depends on win rate, reward:risk, risk per trade and how far the account can fall. This calculator simulates 4,000 sequences in your browser and also shows the typical and longest losing streak you should expect.
Risk of ruin calculator
Simulated over 4,000 random sequences in your browser: each trade wins with your win rate for +R, or loses 1R, sized as a percentage of the balance at the time. It assumes independent trades and a stable win rate, which real trading does not guarantee. It is a stress test of your sizing, not a forecast.
What risk of ruin means
Risk of ruin is the probability that a run of losses takes your account down to a level you decide is "done" - blown, or below the point where you would stop. It depends on four things: your win rate, your reward-to-risk ratio, how much you risk per trade, and how far the account can fall before you call it.
The calculator above runs thousands of simulated sequences using those numbers, so the answer includes the ugly tail cases, not just the average.
The part people get wrong
Two traders with the same strategy can have completely different outcomes because of the risk setting alone. Doubling risk per trade does not double the danger; it compounds it, because each loss is taken from a smaller balance. A run of ten losses is not unusual over a few hundred trades even with a decent win rate, which is what the streak line under the result shows.
The fastest way to feel what a losing streak does is to survive one that costs nothing. Chart Bound runs real historical tape, free.
Play free, no signup →How to use the number
- If the probability is anything other than very small, the honest fix is smaller size, not a better entry.
- Change one input at a time. Dropping risk per trade usually moves the number faster than raising the win rate, and it is the only input fully under your control.
- Check it against your real numbers from a trading journal rather than the numbers you hope for.
What it does not tell you
It assumes every trade is independent and that your win rate and R stay the same, which real trading does not guarantee. It cannot predict your results, and a low number is not a promise of anything. Treat it as a stress test of your sizing, not a forecast.
Frequently asked questions
What is a good risk of ruin?
There is no official standard, and we will not invent one. The useful way to read it is comparative: if halving your risk per trade collapses the number, your sizing was doing the damage, not your strategy.
Does risk of ruin assume I stop trading?
This calculator treats 'ruin' as the account falling to the threshold you set, for example 50% down. Change that field to model a prop firm's maximum drawdown instead.
Why does a high win rate still show a real risk?
Because reward:risk matters as much as win rate, and because losses cluster. A 60% win rate still produces long losing runs over a few hundred trades.
Is my data stored?
No. Everything is calculated in your browser and nothing is sent to us.
Embed this calculator on your site
Free to use, on any site, with no signup: paste this one line where you want the tool to appear. It loads our hosted version, so it stays up to date, and the link under it credits back to this page.
420×620 by default and it scales down to fit a narrower column. Please keep the attribution link.
Keep learning
The fastest way to feel what a losing streak does is to survive one that costs nothing. Chart Bound runs real historical tape, free.
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