Risk of ruin is the probability that a trading account falls to a level where it can no longer recover, given your win rate, reward-to-risk ratio and the share of the account you put at risk per trade.
What risk of ruin crypto trading means in practice
Most traders focus on how much a good system can earn. Survival depends on something else: how large a losing streak the account can absorb. Losing streaks are normal even for profitable systems, and the bigger each bet is, the shorter the streak that does lasting damage.
The key ideas
Losing streaks are built in
With a 50% win rate, a run of five losses in a row is not unusual over a few hundred trades. With a 40% win rate it is more common. The question is not whether a streak will come but what it does to your balance when it does.
The role of risk per trade
If you risk 1% of the account on each trade, ten straight losses cost roughly 9.6% of the account. If you risk 10% per trade, ten straight losses cost about 65%. The same streak is an annoyance in the first case and close to fatal in the second.
Why recovery gets harder
A loss of 50% needs a 100% gain to get back to even. The deeper the hole, the harder the climb, which is why limiting the size of any single loss matters more than chasing a higher win rate.
Expectancy keeps you honest
Expectancy is the average result per trade: win rate times average win, minus loss rate times average loss. A system with negative expectancy will eventually ruin an account at any bet size. Smaller bets only make that slower.
How to put it into practice
- Record your win rate and your average win and loss from real trades, not guesses.
- Calculate expectancy. If it is negative, fix the system before worrying about sizing.
- Choose a risk per trade that lets you survive a streak much longer than any you have seen.
- Set a daily and weekly loss limit that pauses trading when reached.
- Review the numbers monthly and cut size after a bad run instead of increasing it.
A worked example
Imagine a 40% win rate where wins average 2.5 times the size of losses. Expectancy per trade is (0.4 x 2.5R) minus (0.6 x 1R) = 0.4R, so the system is profitable. Yet a streak of eight losses in a row is entirely possible. At 2% risk per trade that streak costs roughly 15% of the account, which is painful but survivable. At 10% risk it costs about 57%, and the account may never recover. The figures are an illustration of the arithmetic, not a promise of results.
Where traders go wrong
- Raising bet size after a win streak and treating luck as skill.
- Doubling down after losses to win the money back.
- Judging a system from a few trades.
- Ignoring fees and slippage, which turn a thin edge into a negative one.
Frequently asked questions
What is a safe risk per trade?
Many traders keep it between 0.5% and 2% of the account. The right number depends on your win rate and how deep a drawdown you can tolerate.
Does a high win rate protect me?
No. A high win rate with small wins and large losses can still have negative expectancy.
Can I calculate risk of ruin exactly?
Only approximately, because real trades are not independent. Use it to compare bet sizes rather than as a precise forecast.
The short version
Losing streaks are normal, so size trades to survive them. The same streak is minor at 1% risk and severe at 10%.
This article is educational and is not financial advice. Crypto assets are volatile and you can lose money, so test any idea with small size first.