Forex Lot Size Calculator

Forex lot size calculation determines how many units of currency to trade in order to risk a specific dollar amount per trade — the cornerstone of professional risk management in foreign exchange trading.

Lot size formula: Lot Size = Risk Amount ÷ (Stop Loss in Pips × Pip Value per Lot)

Pip value formula (for USD-quoted pairs): Pip Value (standard lot) = 0.0001 × 100,000 units = $10 per pip

For non-USD pairs: Pip Value = (0.0001 ÷ Exchange Rate) × Lot Size

What each variable means:

• Pip — the smallest standard price increment in forex; for most pairs: the 4th decimal place (0.0001); for JPY pairs: the 2nd decimal place (0.01)
• Lot types:
  • Standard lot = 100,000 units ($10/pip for major USD pairs)
  • Mini lot = 10,000 units ($1/pip)
  • Micro lot = 1,000 units ($0.10/pip)
  • Nano lot = 100 units ($0.01/pip)
• Risk Amount = how many dollars you’re willing to lose on this trade; professional traders risk 1–2% of account per trade
• Stop Loss in pips = distance from entry to stop-loss exit point in pips

2% risk rule: Risk Amount = Account Balance × 0.02

Full lot calculation: Micro lots = (Risk Amount ÷ (Stop Loss × $0.10)) → round down Standard lots = Micro lots ÷ 100

Reference: pip values for common pairs at 1 standard lot:

• EUR/USD: $10/pip
• GBP/USD: $10/pip
• USD/JPY: ~$9.09/pip (varies with rate)
• USD/CHF: ~$10.20/pip (varies)
• AUD/USD: $10/pip

Worked example: Account: $5,000. Risk per trade: 1% = $50. Trade: EUR/USD, stop loss 40 pips.

• Pip value (standard lot, EUR/USD) = $10/pip
• Risk per standard lot = 40 × $10 = $400 (too high for $50 risk)
• Risk per mini lot = 40 × $1 = $40
• Risk per micro lot = 40 × $0.10 = $4
• Micro lots to use = $50 ÷ $4 = 12.5 → trade 12 micro lots (= 1.2 mini lots)

At 12 micro lots: actual risk = 12 × $4 = $48 (within the $50 budget). If the trade hits stop loss, the account loses $48 — exactly 0.96% of the $5,000 account. Risk controlled.