A standard lot equals 100,000 units. Lot size affects profit, loss, and how quickly you hit risk limits.
Use this formula: Lot Size = (Risk × Balance) ÷ (Stop Loss × Pip Value). Always know your numbers.
Example: $10,000 account, 1% risk, 50 pip stop loss, $10 pip value = 0.2 lot size.
MT4 doesn’t include a calculator by default, but you can add custom scripts for quick lot size calculations.
Don’t risk over 1–2% per trade. Adjust lot size for news events and volatile market conditions.