Lot size and risk management for Expert Advisors
Most traders who lose money with an EA do not lose because of the strategy alone. They lose because trades are too large for the account. Risk management decides how long you can stay in the game.
Decide how much you can lose per trade
A common guideline is to risk a small fixed percentage of the account on each trade, often 1 percent or less. The exact number is your decision and depends on your situation. Never trade money you cannot afford to lose.
The position sizing formula
Lot size = (account balance × risk percent) ÷ (stop loss distance × value of one point per lot).
Example: a 5,000 USD balance risking 1 percent is 50 USD. If the stop loss is 100 pips and one pip is worth 10 USD per standard lot, then lot size is 50 ÷ (100 × 10) = 0.05 lots. Your broker's contract specification gives the exact pip value for each symbol, so check it, especially for gold and oil.
Respect drawdown
Drawdown is how far the account falls from its peak. A 50 percent drawdown needs a 100 percent gain to recover. Choose settings so that the largest drawdown seen in testing is one you could tolerate in real life, and remember live drawdown can exceed the backtest.
Practical rules
- Start on a demo account, then go live with the smallest lot size the broker allows.
- Increase size gradually and only after a period of behaviour you understand.
- Do not add lots to recover losses.
- Keep margin level high; avoid using most of your free margin.
- Check for major news and for weekend gaps if your EA holds positions over them.
Risk warning
Trading leveraged products such as forex, gold and CFDs carries a high risk of loss and is not suitable for everyone. Nothing in this guide is financial advice.
Frequently asked questions
What lot size should I use?
It depends on your balance, your stop loss distance and how much you are willing to lose on a trade. Use the position sizing formula and the smallest size that fits your plan.
Is a bigger lot size better?
No. A bigger lot size increases both potential profit and potential loss, and makes drawdown larger.
What is pip value?
The amount of money one pip move is worth per lot. It differs by symbol and account currency, so read it from the broker's contract specification.
Trading foreign exchange, gold and CFDs carries a high level of risk and may not be suitable for all investors. Past performance, backtests and live results do not guarantee future returns. This guide is general education, not financial advice.