Position sizing explained
Position sizing is the quiet skill that separates traders who last from those who don’t. It is the maths that turns “risk 1%” into a real trade size. Here is how to work it out, with a simple example.
Ask two traders to take the same trade and they can still end up worlds apart, not because of where they entered, but because of how much they put on. Position sizing is the step that decides how big a trade to place, and it is where the abstract idea of “only risk 1%” becomes an actual number of lots or units. Skip it, and even a great entry can hurt you. Get it right, and every trade risks the same small, controlled amount.
What position sizing is
Position sizing answers one question: how large should this trade be so that, if my stop-loss is hit, I lose only the amount I chose to risk? It links three things, your account balance, your risk percentage, and your stop distance, into a single trade size. It is the mechanism that makes risk management real rather than theoretical.
The three inputs
- Account balance, the total in your trading account.
- Risk percentage, how much of that you will risk per trade, usually 1%.
- Stop distance, how far your stop-loss sits from your entry.
From those three, the position size falls out automatically. You never guess it.
The simple formula
The core of it is one line: risk amount ÷ stop distance = position size. First work out your risk amount, 1% of your balance. Then divide it by the distance from entry to stop. The result is how big your position should be so that hitting the stop costs exactly your risk amount, no more.
A worked example
Say you have a $2,000 account and risk 1%, so your risk amount is $20. You want to buy, and the chart tells you the stop belongs 40 pips away. Your position size is whatever makes a 40-pip move equal $20, so each pip is worth $0.50. If instead the stop only needed to be 20 pips away, each pip could be worth $1.00, a larger position, but still only $20 at risk. The risk stayed the same; the size changed to fit the stop.
| Account | Risk (1%) | Stop distance | Position size |
|---|---|---|---|
| $2,000 | $20 | 40 pips | $0.50 / pip (smaller) |
| $2,000 | $20 | 20 pips | $1.00 / pip (larger) |
| $2,000 | $20 | 10 pips | $2.00 / pip (largest) |
Why it matters more than being right
You cannot control whether a trade wins, but you fully control your size. Two traders running the same strategy can end up in completely different places: the one who sizes every trade to risk 1% rides out losing streaks, while the one who over-sizes gets wiped out by the same run of losses. Consistent sizing is the difference between a temporary drawdown and a blown account.
Make it a habit
Before every trade, run the same three-step check: what is 1% of my account, where does my stop go, and what size makes those two line up? Many platforms and free calculators do the maths for you, so there is no excuse to eyeball it. Size every trade the same disciplined way and your risk stays flat no matter what the market throws at you.
Find a broker with flexible lot sizes
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This guide is for educational purposes only and is not financial advice. Trading forex and CFDs carries a high level of risk and can result in the loss of all your capital. Most retail investor accounts lose money. Make sure you understand the risks and seek independent advice if needed before trading.