How Much to Risk per Trade: Start From Your Worst Day
How much to risk per trade, worked out from the losing streak you must survive: streak odds for 35% to 50% win rates and rules for personal and prop accounts.
Most traders pick their risk per trade from their best trade: "this setup can make $600, so I'll risk $300." The account doesn't care about your best trade. It cares about your worst run of trades, and that is where the risk number should come from.
Losing streaks are longer than they feel
These are the chances of at least one losing streak of a given length somewhere in 100 trades, computed exactly for independent trades:
| Losses in a row | 50% win rate | 40% win rate | 35% win rate |
|---|---|---|---|
| 5 | 81% | 98% | 100% |
| 6 | 55% | 87% | 96% |
| 8 | 17% | 49% | 69% |
| 10 | 4% | 20% | 37% |
A 40% win rate is normal for a strategy that aims for twice its risk. At that win rate, 8 losses in a row over 100 trades is close to a coin toss. And losing streaks are not the only way down: a mix of losses with a few small wins can reach the same depth.
The rule: divide your room by the streak you must survive
Risk per trade = room ÷ losses in a row you want to survive
- Room is what you can lose before something ends: the distance to a prop firm's max loss, the daily loss limit, or the amount of a personal account you are willing to lose.
- Losses to survive comes from the table: for a 40% win rate, surviving 10 in a row covers 80% of 100 trade stretches.
| Room | Survive 6 | Survive 8 | Survive 10 |
|---|---|---|---|
| $2,000 max loss | $333 | $250 | $200 |
| $1,000 daily limit | $166 | $125 | $100 |
| $3,000 max loss | $500 | $375 | $300 |
Then turn the dollar risk into contracts with the position sizing formula.
Why the 1% rule doesn't fit prop accounts
The classic advice is to risk 1% to 2% of the account per trade. On a personal account that is sensible. On a $50,000 prop firm account it is misleading: 1% is $500, but the account fails after a $2,000 drawdown, so each trade risks a quarter of your real room. Four losses and the evaluation is over. Size from the room, not the account size. Trailing drawdown explained shows how that room moves.
Check the daily limit too
Your per trade risk must also fit the day. With a $1,000 daily loss limit and $333 per trade, three losses end the day. If your plan allows four trades a day, $250 fits, $333 doesn't.
When to change your risk
Change it by rules you set before trading, never by mood:
- Up, when the room grows: for example when a trailing drawdown stops trailing and the floor is fixed.
- Down, after a set drawdown, for example cut risk in half after losing half the room.
- Never up after a loss to win it back.
Find your own streaks
The table assumes independent trades at a fixed win rate. Your real numbers come from your own trades: record at least 100 setups and look at your actual longest losing streak and deepest drawdown. ChartTrainer's journal records every practice trade with its result in R, and its backtester charts how far a strategy fell below its peak and estimates the chance of passing an evaluation at your risk. Practice on replayed real market days from the prop firm simulator.
Questions
- How much should I risk per trade?
- Enough that the losing streak you can realistically expect does not end your account or your day. Divide the room you have, your drawdown or daily loss limit, by the number of losses in a row you want to survive.
- Is the 1% rule right for prop firm accounts?
- Not directly. 1% of a $50,000 account is $500, but the account can only lose $2,000 to $3,000 before it fails, so 1% of the account is a quarter of your real room. Size from the drawdown, not the account size.
- How many losing trades in a row should I expect?
- More than it feels like. With a 50% win rate, there is an 81% chance of at least 5 losses in a row somewhere in 100 trades. With a 40% win rate, there is a 49% chance of 8 in a row.
- Should I risk more after a winning streak?
- Only by a rule decided in advance, for example raising risk as the drawdown stops trailing. Raising risk because you feel confident, or after a loss to win it back, is how normal streaks become blown accounts.