Position Size Calculator
Find the exact lot size that risks the right amount on every trade. Enter your account balance, risk per trade, pair and stop-loss — the calculator does the rest.
Dollar risk
$100.00
Position size
0.50 lots
Units
50,000
Assumes a USD-denominated account. JPY-cross and non-USD-quoted pairs use reference rates, so live broker margin may vary ±5%. Always round the lot size down to fit your risk budget.
Why fixed-% risk works
Position sizing solves the biggest problem in retail trading: inconsistent risk. Without it, traders unknowingly risk 0.5% on some trades and 8% on others. A single oversized loser can erase weeks of gains.
Risking a fixed percentage of your account on every trade compounds losses logarithmically instead of linearly. Ten losing trades at 1% leaves 90.4% of your account intact. Ten losing trades at 5% leaves 59.9%. The difference is survival.
The formula
Position size (lots) = (Account Balance × Risk %) ÷ (Pip Value per Lot × Stop Loss Pips)
Example: $10,000 account, 1% risk, EURUSD ($10 per pip per lot), 25-pip stop-loss → $100 / (10 × 25) = 0.40 lots.
How this fits your trading routine
- Read the FXBias daily briefing to get bias, entry and stop-loss for each pair.
- Plug stop-loss pips and pair into this calculator — get lot size in seconds.
- Trade with consistent risk, regardless of how wide or tight the stop-loss is.
- Pair with the pip value calculator when comparing trades across pairs.
Frequently asked
What is position sizing in forex?
Position sizing is the process of deciding how many lots to trade based on how much money you are willing to lose if your stop-loss is hit. It is the single most important risk-management tool — far more important than where you enter.
How much should I risk per trade?
Most professional traders risk 0.5–2% of their account per trade. Risking more than 2% accelerates drawdown dramatically: a 5-trade losing streak at 5% per trade reduces a $10,000 account to $7,738. At 1% per trade the same streak leaves $9,510.
How is the formula derived?
Position size (lots) = (Account Balance × Risk %) ÷ (Pip Value per Lot × Stop Loss in Pips). The numerator is your dollar risk; the denominator is what you lose per lot if the stop is hit.
Why round down the lot size?
Rounding up means you risk slightly more than your target. Rounding down means you risk slightly less. Always err on the side of less risk — over hundreds of trades the difference compounds in your favour.
Sized your trade? Get the daily bias to back it up.
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