Forex guide
Position sizing: decide the loss before the trade
Position sizing is the bridge between a trading idea and the real money at risk. It answers a simple question: if this trade fails, how much can I lose?
Start with account risk
A common beginner rule is to risk a small fixed percentage of account equity on each trade, often 1% or less. The exact number is personal, but it should be chosen before looking at the chart. If your account is R10,000 and you choose 1% risk, the maximum planned loss is R100.
This rule keeps one trade from becoming too important. Losing trades are part of trading. The problem is not a planned loss; the problem is a loss large enough to change your behaviour on the next trade.
Use stop distance honestly
The stop loss should sit where the trade idea is wrong. It should not be squeezed close to the entry just so the position can be larger. If the chart needs a wider stop, reduce the trade size. If the reduced trade size feels unsatisfying, skip the trade and wait for a cleaner setup.
The basic sizing process
- Write your account balance.
- Choose the percentage you are prepared to risk.
- Convert that percentage into a rand amount.
- Measure the distance between entry and stop loss.
- Calculate the position size so the stop-loss hit equals the planned rand risk.
Example thinking
Suppose a trader has R10,000 and risks 1%, or R100. If the planned stop distance is wide, the trade size must be smaller. If the stop distance is narrow but realistic, the trade size may be larger while the rand risk remains the same. The goal is consistency: different trades, different stop distances, same controlled risk.
Position sizing also helps with emotional control. When the loss is known in advance and acceptable, there is less temptation to move the stop, average down or close a good trade too early because the position feels too big.
Rules worth writing down
- Never increase position size to recover a previous loss.
- Never widen a stop without recalculating risk.
- Never open several correlated trades as if they are independent.
- Stop trading for the day when the daily loss limit is reached.
Why fixed lot sizes can be dangerous
Some beginners choose a lot size and use it on every trade. That feels simple, but it ignores stop distance and volatility. A small stop on a quiet pair and a wide stop on a volatile pair do not create the same risk. If the lot size stays fixed while the stop distance changes, the rand amount at risk changes too.
Position sizing should adapt to the trade. The account risk can remain consistent even when the market conditions are different. That consistency is what helps a trader evaluate results. If every trade risks a different random amount, it becomes difficult to know whether the strategy is improving or whether a few oversized trades are distorting the account.
Think in risk units
Many traders use the letter R to describe risk. If your planned risk is R100, then one R equals R100. A loss at the stop is minus one R. A profit of R200 is plus two R. This helps you compare trades without being distracted by account size or pair type.
Risk units also make review easier. You can ask whether your winning trades are large enough compared with your losing trades, whether you cut winners too early, or whether you let losers grow beyond the original plan. The focus shifts from emotional money amounts to process quality.
Position sizing and psychology
If a trade is too large, the trader usually knows before the stop is hit. They check the phone too often, move the stop, close too early or start looking for opinions that support the position. This is not only a technical problem; it is a sizing problem. The position is too large for the trader's current emotional tolerance.
There is no shame in trading smaller. Smaller size gives you room to practise execution. Once the process is stable over a meaningful sample, size can be reviewed gradually. Jumping from demo to large live trades often teaches fear faster than it teaches skill.
Example position-size worksheet
| Account balance | Write the current account equity, not the amount you hope to have after the trade. |
|---|---|
| Risk percentage | Choose a fixed percentage before looking for entries. |
| Rand risk | Convert the percentage into money. This is the amount you accept losing. |
| Stop distance | Measure where the trade idea is invalidated. |
| Trade size | Adjust size so the stop-loss hit equals the planned rand risk. |
What to do after a losing trade
After a planned loss, record it and step away for a moment. Do not immediately search for a trade that can "get the money back". Recovery thinking is one of the fastest ways to break a position-sizing rule. The next trade should qualify on its own, with the same risk process as the previous one.
If you break the rule, reduce size for the next session or return to demo until discipline returns. Protecting behaviour is more important than protecting pride.
Position sizing for several open trades
One trade risking 1% may be acceptable under your plan. Five trades each risking 1% may not be acceptable, especially if they depend on similar market conditions. A trader needs both a per-trade risk rule and a total-risk rule. The total-risk rule says how much of the account may be at risk across all open positions.
For example, a trader might risk no more than 1% per trade and no more than 2% across all open positions. That means opening a third trade may require reducing size or skipping the setup. This rule stops the account from quietly becoming overexposed.
Adjusting size after account changes
Position size should update as account equity changes. If the account grows, the rand value of a fixed percentage grows slowly. If the account falls, the rand value should shrink. This prevents a drawdown from becoming worse because the trader keeps using the old, larger size.
Some traders recalculate before every trade. Others update weekly. The important point is that risk should be connected to current equity, not to the account high-water mark or the trader's hopes for recovery.
Why small risk can still teach a lot
Beginners sometimes believe they must risk more to learn faster. Usually the opposite is true. Smaller risk keeps the emotional temperature low enough to observe mistakes. You can still learn execution, journaling, patience, broker behaviour and market movement while risking very little.
Large risk often teaches only fear. It makes the trader focus on money instead of process. Keep risk small until your behaviour is boringly consistent.