Change ACCOUNT CURRENCY and CURRENCY PAIR
A Lot Size Calculator is arguably the most important tool for any serious trader — it answers the question: how many lots should I trade to keep my risk under control?
What inputs does it need?
- Account balance — your total trading capital
- Risk percentage — how much of your account you’re willing to lose on this trade (typically 1–2%)
- Stop-loss in pips — how many pips away your stop-loss is from your entry
- Currency pair — to look up the pip value
- Account currency — so everything converts correctly
What does it calculate?
Position Size = (Account Balance × Risk %) ÷ (Stop-loss in pips × Pip Value)
Example with a $10,000 account, 1% risk, 50-pip stop on EUR/USD:
- Risk amount = $100
- Pip value on 1 standard lot = ~$10
- Position size = $100 ÷ (50 × $10) = 0.2 lots
Why is it useful?
- Keeps every single trade within your predefined risk tolerance
- Adjusts automatically — wider stops mean smaller position, tighter stops mean larger position
- Removes emotion from sizing decisions entirely
- Protects your account from a single bad trade wiping out too much capital
The golden rule it enforces: Never risk more than 1–2% of your account on any single trade. A trader risking 10% per trade only needs 10 consecutive losses to lose everything. At 1%, you’d need 100 — giving you time to identify and fix what’s going wrong.
How it connects to other calculators: It sits at the centre of the suite. It pulls pip value from the Pip Value Calculator, uses your stop-loss distance to determine sizing, and feeds the result into the Profit Calculator to confirm your risk/reward ratio before you click buy or sell.