Trading Risk Management: Position Size and Stop-Loss

Risk per trade, the position-size formula, stop placement, risk/reward ratio and drawdown: the basics for surviving in crypto trading.

Trading · Débutant · 10 min read · Publié le September 28, 2026

The essentials

This content is general information for educational purposes. It is neither investment advice nor an incitement to trade.

Why risk management comes first

The regulators' numbers are clear. An AMF study covering nearly 14,800 active retail clients trading CFDs and Forex in France between 2009 and 2012 found more than 89% of clients losing money, with an average loss of about €10,900 per client. The study also notes that clients who traded more often or with larger positions lost proportionally more.

At the European level, ESMA (the European Securities and Markets Authority) reported in 2018 that 74 to 89% of retail accounts lost money on CFDs depending on the country. It then capped the leverage offered to retail clients on these products, with a limit of 2:1 for cryptocurrency CFDs, the lowest of all categories. The AMF subsequently made these measures permanent in France starting in 2019.

These studies cover CFDs, not crypto perpetual contracts directly. But the mechanism is the same: leverage, fees, fast decisions. The practical conclusion is simple: without risk rules written down in advance, the probability of losing is high.

Step 1: set your risk per trade

The risk per trade is the maximum sum you accept to lose if the trade goes wrong and your stop is hit. It's expressed as a percentage of the capital dedicated to trading.

A common rule is not to exceed 1% of capital per trade, or even less in crypto where volatility is high. Some traders in traditional finance talk about 2%. The idea isn't that any number is magic, but that it be small, fixed and decided before you open the position.

Why so little? Because losing streaks happen to everyone. Compare the effect of 10 consecutive losses:

Risk per trade	Capital remaining after 10 losses
1%	about 90.4%
2%	about 81.7%
5%	about 59.9%

With 1% risk, ten losses in a row are unpleasant but manageable. With 5%, you've lost 40% of your capital and you're in a zone where recovery becomes very difficult.

Step 2: place the stop in the right spot

The stop (or stop-loss) is an order that automatically closes your position if the price reaches a given level. For the technical details of order types, see our guide on market, limit and stop orders.

The most important rule: the stop goes where your scenario is invalidated, not where the loss seems "bearable" to you. A few usual reference points:

Below a support (a zone where the price has bounced several times) for a long position, above a resistance for a short position.
Based on volatility: an asset that moves 5% a day can't handle a 1% stop. Indicators like the ATR (Average True Range, the average size of candles) are used to calibrate this distance.
Beyond the obvious zones: a stop placed right on a round number or just below a very visible low is more likely to be hit by a simple wick.

The stop is decided before entry. Moving a stop further away because the price is approaching it amounts to increasing your risk along the way.

Stop market or stop limit?

On most platforms, you have a choice between two variants. A stop market triggers a market order: the exit is nearly guaranteed, but the execution price may be worse than expected (this is slippage). A stop limit triggers a limit order: the price is controlled, but the order may not be filled if the market moves too fast. For a protective stop, many traders prefer the stop market precisely because it gets you out.

On perp DEXs and derivatives exchanges, also check which price triggers the stop (last price, mark price, median price) and use the reduce-only option, which guarantees that the order can only reduce your position and never open one in the opposite direction.

Step 3: calculate the position size

This is where everything comes together. The basic formula:

Position size = (Capital × Risk per trade) ÷ Distance to stop (in %)

The result is the total value of the position (called the notional), not the margin you deposit.

A concrete example

You have €5,000 in your trading account and set 1% risk per trade, meaning a maximum loss of €50.

You want to buy BTC at $60,000. Your analysis places the invalidation below a support at $57,000. The distance to the stop is therefore $3,000, or 5% of the entry price. (To keep it simple, we reason as if €1 were worth $1.)

Position size = 50 ÷ 0.05 = €1,000 of notional.
In BTC: 1,000 ÷ 60,000 ≈ 0.0167 BTC.
If the stop is hit: 0.0167 × 3,000 ≈ €50 loss, excluding fees and slippage.

If your stop had to be 10% away, the position would drop to €500. The loss in euros would stay the same: it's the size that adapts to the stop, not the other way around.

And what about leverage?

Leverage does not change your risk if the position size is calculated this way. In the example, whether you deposit €1,000 with no leverage, €200 with 5x leverage or €100 with 10x leverage, the loss at the stop remains about €50. What leverage changes is the margin tied up and, above all, the position of the liquidation price.

Imperative rule: your liquidation price must be well beyond your stop. If liquidation occurs before the stop, you lose more than planned and also pay liquidation fees. With high leverage, liquidation moves dangerously close to the entry. To understand this mechanism, see our guide on isolated and cross margin.

Don't forget fees

Opening and closing fees (and funding on perpetuals) add to the loss at the stop. With very tight stops and large positions, they can represent a significant share of the real risk. Include them in your calculation, at least roughly.

The risk/reward ratio and the win rate

The risk/reward ratio (or R:R) compares what you're aiming for to what you're risking. If you risk €50 to aim for €100, the ratio is 1:2.

This ratio is tied to the minimum win rate needed to avoid losing money (excluding fees):

Risk/reward ratio	Breakeven win rate
1:1	50%
1:2	about 33%
1:3	25%

The formula: breakeven rate = 1 ÷ (1 + R), where R is the targeted gain divided by the risk. A trader who wins on average twice what they lose can stay profitable while being wrong more often than right. Conversely, aiming for tiny gains with wide stops forces you to be right almost all the time.

Be careful, though: a distant target only makes sense if it's realistic given the market. Showing a 1:5 ratio on paper is pointless if the price almost never reaches the target.

Drawdown: why big losses are so costly

The drawdown is the decline in capital from its peak. The trap is mathematical: to get back to the starting point, you need a gain larger than the loss suffered.

Loss suffered	Gain needed to get back to zero
-10%	+11.1%
-20%	+25%
-50%	+100%

The formula: required gain = loss ÷ (1 - loss). After -50%, you need to double the remaining capital. This is why a small risk per trade is so important: it keeps the drawdown from sinking into the zone where recovery becomes unrealistic.

Many traders also set overall limits: a maximum loss per day or per week, beyond which they stop trading until the next period. This cuts off the spirals where you try to "win it back."

Keeping a trading journal

A trading journal is a simple table where you record each trade. It's the most underrated tool: without data, it's impossible to know whether your method works or whether you just got lucky.

Useful columns:

date, asset, direction (buy or sell);
entry price, stop, target, position size;
planned risk in euros and in R, actual result in R;
fees paid;
reason for entry, whether the plan was followed, emotional state.

Expressing results in R (multiples of the initial risk) lets you compare trades of different sizes. A trade that earns €100 on €50 risked is worth +2R; a stop hit is worth -1R. After a few dozen trades, you can calculate your win rate and your average gain in R, and check whether your system has a positive expectancy.

Mistakes to avoid

Choosing the position size by feel, then placing the stop where the loss "doesn't hurt too much." That's the reverse of the right method.
Confusing margin and risk: depositing €100 of margin with 50x leverage doesn't mean you're risking €100, nor that this is all you're risking in terms of your strategy.
Trading without a stop while telling yourself you'll keep watch. One turbulent night or a dropped connection is enough.
Moving your stop further away when the price approaches it, or deleting it.
Increasing size after a loss to win it back quickly.
Leaving the liquidation closer than the stop because of excessive leverage.
Ignoring fees and funding, which eat into small gains and add to losses.
Not writing anything down, and so repeating the same mistakes without seeing them.
Buying a prop firm challenge without a risk plan: a challenge's daily loss limit and maximum drawdown are even tighter than your own limits. See how a crypto prop firm works and our crypto prop firm comparison.

Checklist before every trade

My trading capital and my risk per trade are defined (for example 1%).
My stop is placed at the invalidation level, before entry.
I've calculated the position size with the formula.
My liquidation price is well beyond my stop.
My target gives a risk/reward ratio consistent with my win rate.
I haven't hit my loss limit for the day or the week.
The trade is recorded in my journal.

Key takeaways

First decide how much you're willing to lose per trade, as a fixed, modest percentage of capital.
Place the stop at the level where your idea is invalidated, then calculate the size: Capital × Risk ÷ Distance to stop.
Leverage doesn't change the risk if the size is properly calculated, but liquidation must stay beyond the stop.
A good risk/reward ratio lets you be profitable even with fewer than 50% winning trades.
Big losses are disproportionately hard to recover from: -50% requires +100%.
A trading journal turns your impressions into usable data.