Margin requirement is determined using the leverage allowable by that broker.
Without leverage you cannot determine your margin deposit to open a position.
This is automatically done with every broker but it helps to know what you are doing and why you should or not be doing something.
For example, you have $400 and wish to open a mini account where 1 pip = $1
The maximum leverage allowed by the broker is 20:1
You trade EURUSD and see a buy opportunity at 1.5246.
You want to risk 30 pips for the trade which is 6% of your account.
Already, you would have $470 as balance after trade is executed. But that is not all. The broker needs a good faith deposit to maintain the position.
Your margin requirement is 5% (1/20 × 100)
Your required margin is $762.3 (5/100 × 10000 × 1.5246).
The trade will not be executed. The platform will return an “insufficient balance” error. This is because you are unable to meet the margin requirement.
If the leverage is, say, 100:1
Margin requirement will be 1%
Required margin is now $152.46
The trade will be executed but your usable margin is $397.54, not $470.
If the trade results in a loss, your new balance is $470 - spread
This is how leverage plays a vital role in money management
With position sizing, you want to scale down your lot size to allow greater room for stoploss with the same risk.
You want your stoploss to be 70 pips risking $50.
$50/70 = $0.7
¢70 per pip
To open a position, where your leverage is 20:1, your margin requirement is 5% but your new required margin is $76.23. That means you are able to open a position but your gains and losses will mostly be lesser.
No matter how you look at it, the knowledge of leverage ratio is extremely important if you really want to account for every cent or dollar invested.