Leverage in forex trading allows you to control a large position with a relatively small amount of capital. While your broker may offer leverage of 100:1 or more, the effective leverage you use depends on your position size relative to your account balance. Effective leverage is arguably the most important risk factor in forex trading, as it determines how much of your account is at risk with each pip movement.

Key formulas include: Effective Leverage = Position Size / Account Balance, Margin Required = Position Size / Leverage Ratio, Free Margin = Equity - Margin Required, and Margin Level = (Equity / Margin Required) x 100. When margin level drops below 100%, you receive a margin call. Most brokers will automatically close positions if margin level falls to 50% (the stop-out level).

For example, with a $10,000 account and a $100,000 position, your effective leverage is 10:1 even if your broker offers 100:1 leverage. At 100:1 broker leverage, the margin required is $1,000, leaving $9,000 in free margin. Your margin level is 1,000%. Each pip is worth approximately $10, so a 100-pip move against you would cost $1,000 or 10% of your account. Professional traders typically keep effective leverage between 2:1 and 10:1, regardless of the maximum leverage their broker offers.