Forex Position Size Calculator
Calculate the correct forex lot size based on account balance, risk percentage, stop-loss in pips, and currency pair — similar to myfxbook's position size tool.
About the Forex Position Size Calculator
Position sizing is the single most important risk management decision in forex trading. Trading too large a position relative to your account balance means a single losing trade can wipe out a significant portion of your capital. Trading too small means you leave potential returns on the table. The goal of position sizing is to risk a defined, consistent percentage of your account on each trade — typically 0.5% to 2% for professional traders.
The position size calculation is: Lots = (Account Balance × Risk%) / (Stop Loss in Pips × Pip Value per Lot). For example, with a $10,000 account, risking 1% ($100), on a 20-pip stop loss on EUR/USD (where 1 standard lot has a pip value of $10), the correct position size is $100 / (20 × $10) = 0.5 standard lots. This ensures that if your stop-loss is hit, you lose exactly $100 — 1% of your account.
Consistent position sizing is what separates professional traders from amateurs. A trader who risks varying amounts on different trades — sometimes 5%, sometimes 0.5% — will have wildly unpredictable drawdowns and psychological responses to losses. Fixed percentage risk keeps the account growing geometrically and limits emotional decision-making by making losses predictably small.
Forex Risk Management Fundamentals
The standard advice among professional forex traders is to risk no more than 1–2% of account equity per trade. At 1% risk, a trader would need 100 consecutive losing trades to lose all their capital — statistically impossible for any strategy with even a slight edge. At 5% risk, just 20 consecutive losses wipe out the account, a realistic possibility during a drawdown period even for profitable strategies. The math of compounding losses is asymmetric: losing 50% requires a 100% gain just to break even.
Stop-loss placement is the other half of the position sizing equation. Your stop-loss should be placed at a technically meaningful level — below a support zone, behind a swing low, or beyond a key moving average — not at a fixed pip distance. The position size calculation then takes that technically derived stop distance and determines how many lots to trade to keep the dollar risk at your target percentage. Never choose a stop-loss to fit a convenient lot size; always start with the technical level and let position size be the variable.
Pip values are straightforward for US-dollar-quoted pairs (EUR/USD, GBP/USD, AUD/USD) where $10 per pip per standard lot is a reliable approximation. For cross pairs where USD is the base currency (USD/JPY, USD/CAD, USD/CHF), the pip value in USD varies with the exchange rate. Our calculator provides approximate pip values — for precise values in real time, use your broker's built-in calculator or confirm the exact pip value before trading.