Introduction
One of the most overlooked aspects of trading is position sizing — deciding exactly how much to trade on each position. Get this wrong, and even a strong strategy can suffer severe drawdowns or fail over time. Get it right, and you can survive long losing streaks and still come out profitable.
What is Position Sizing?
Position sizing is the process of determining how many units (lots) to trade on a given position, based on: - Your total account balance - The percentage of your account you are willing to risk - The distance to your stop-loss
It is the bridge between your risk management rules and the actual trade you place.
The 1% and 2% Rules
The most widely used position sizing rule is to never risk more than 1–2% of your total account balance on any single trade.
As a guideline, risking 1%–2% per trade helps keep losing streaks manageable and can reduce the chance of severe drawdowns.
| Account Balance | 1% Risk | 2% Risk |
|---|---|---|
| $1,000 | $10 | $20 |
| $5,000 | $50 | $100 |
| $10,000 | $100 | $200 |
| $50,000 | $500 | $1,000 |
How to Calculate Your Lot Size
Formula:
Lot Size = (Account Balance × Risk %) ÷ (Stop-Loss in Pips × Pip Value)
Worked Example: - Account balance: $10,000 - Risk per trade: 1% = $100 - Stop-loss: 50 pips - Pip value for EUR/USD (standard lot): $10 per pip
Lot Size = $100 ÷ (50 × $10) = $100 ÷ $500 = 0.20 lots
So you would trade 0.20 lots (a mini lot) to risk exactly $100 on this trade.
Why Consistent Position Sizing Matters
Consider two traders, both with a 50%-win rate and a 1:2 risk-to-reward ratio:
The mathematics of trading survival depends on keeping losses small and consistent. A 50% loss requires a 100% gain just to break even. Consistent position sizing prevents catastrophic drawdowns.
- Trader A uses consistent 1% position sizing → Grows account steadily over time
- Trader B varies position size based on "confidence" → One large losing trade wipe out weeks of gains
Position Sizing in MT5
On MetaTrader 5, you set your lot size in the order ticket before executing a trade. Use a position size calculator (available as an MT5 indicator or online tool) to determine the correct lot size before each trade.
Common forex lot references are: - 1 Standard Lot = 100,000 units - 1 Mini Lot = 10,000 units (0.10) - 1 Micro Lot = 1,000 units (0.01)
Exact contract specifications can vary by broker and instrument.
Many beginners choose smaller sizes such as micro lots (0.01), where available, to reduce risk while learning.
Common Position Sizing Mistakes
1. Increasing size after a win — Overconfidence leads to oversized positions that wipe out previous gains.
2. Increasing size to "recover" losses — Revenge trading with larger positions is the fastest way to blow an account.
3. Using the same lot size regardless of stop-loss — A 10-pip stop and a 100-pip stop require very different lot sizes for the same dollar risk.
4. Ignoring pip value differences — Pip values vary between currency pairs. Always calculate for the specific pair you are trading.
Key Takeaways
- Understand the concept before trading live.
- Practise with a demo account before risking real capital.
- Use risk management on every trade.