AuthorBy Jeffrey Cammack
Updated: August 27, 2019

In this article we are going to look at what the margin is and how it changes dependent on leverage, position size, currencies traded and your account currency. We will also learn how to calculate margins in different trading scenarios.

What is the Margin?

The margin is the amount of money that your Forex broker will require from you to open a trade. In financial terms, it is the collateral needed to access the leverage required for your trade. To calculate it accurately you need to know four things:

  1. The amount of leverage you are using
  2. The position size of your trade
  3. The base currency of your trade
  4. Your account currency

Calculating Margin: Leverage

Margin is inversely proportional to leverage and can be expressed as a percentage of the full amount of the position.

Margin = 1/Leverage

Example 1: A 50:1 leverage ratio means a margin requirement of 1/50 = 0.002 = 2% margin requirement. Example 2: A 100:1 leverage ratio means a margin requirement of 1/100= 0.001 = 1% margin requirement. Let’s assume that you have a balance of 5,000 USD in your trading account.  You decide to trade one lot (100,000 USD) of the USD/EUR pair. The table below shows your margin size relative to varying amounts of leverage: As you can see, with 1:50 leverage you use almost half of your account balance as the margin. This doesn’t leave you with much capital to make additional trades, especially if your trade performs poorly and you lose your investment. Equally, lower margin requirements mean more money in your account to use for other trades. The higher the leverage used, the smaller your margin will be. It’s important to note that no matter the leverage, the margin requirement can vary significantly depending on which currency pair you are trading. This is because margin is always calculated in the base currency and then converted to your account currency.

Calculating Margin: Examples

Before you place a trade, you should have a rough idea of the margin requirement. This will get easier to approximate the more experience you have with trading. To calculate the margin accurately, you can use the following formula as long as the base currency is the same as your account currency:

Margin Requirement = (Position Size) / Leverage

Let’s consider the following example:

  • Buying AUD/USD
  • Position Size = 300,000 (3 lots)
  • Account Leverage = 1:100
  • Account Currency: AUD

Margin Requirement = 300,000 / 100 = 3000 AUD

So you need to have at least 3000 AUD in your account as collateral to open that position. Otherwise, your order will be rejected due to insufficient margin. Let’s now compare the margin needed for two different currency pairs and see how this can cause significant variations: Example 1:

  • Pair: GBP/AUD
  • Position Size: 100,000 (1 Lot)
  • Leverage: 1:100
  • Account Currency: USD
  • Margin Requirement = USD 1246.1

Example 2:

  • Pair: AUD/USD
  • Position Size: 100,000 (1 Lot)
  • Leverage: 1:100
  • Account Currency: USD
  • Margin Requirement = USD 692.6

In Example 1 (GBP/AUD) the margin requirement is almost double that for Example 2 (AUD/USD), despite the leverage and position size being the same – lets find out why. Lets looks at Example 1 first: The GBP/AUD is a cross pair not involving USD – our account currency. For currency pairs not quoted in your account currency, you need an additional calculation:

Margin Requirement = [(Position Size) / Leverage] * Base/Account Currency Exchange Rate

Instead of using the GBP/AUD exchange rate to calculate our margin we use the Base/Account Currency exchange rate (GBP/USD).  The base currency from the GBP/AUD pair is the GBP, while our account currency is USD, so we need the rate of GBP/USD (1.2461) to calculate the margin requirement in USD. So the formula above looks like this:

Margin Requirement = [100,000 / 100 ] * 1.2461 


Margin Requirement = 1246.1 USD

Now, let’s look at Example 2: Even though the USD is one of our currency pair, it is not the base pair – that is AUD. So we have to convert the position size from AUD to USD, our account currency. The AUDUSD exchange rate is 0.6926 so our formula looks like this:

Margin Requirement = [100,000 / 100 ] * 0.6926 


Margin Requirement = 692.6 USD

Conclusion Having a good understanding of margin requirements is essential to trading because it directly affects the size and number of trades that you can safely make. The lower your leverage, the higher your margin requirements will be, and you will need to put up more money as collateral to open a position. Finally, always be aware that trading a pair with a base currency that is not your account currency can drastically alter your margin size. Before you open this type of trade always calculate the margin requirements first.

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