Your calculation is correct, but your interpretation is not.
In the event of a margin call your broker will liquidate your positions, so you’re only going to lose the amount equal to your unrealized loss. In other words, your margin used is the account balance that will be left after a margin call. As a general rule of thumb, the more [B]actual leverage[/B] you use the less money you’re going to lose when you get margin called.
Just a caveat though, some brokers like Oanda will only issue a margin call once your Margin Closeout Value (a variant of equity) falls down to or below half the margin used; However, they will liquidate your positions if your account stays undermargined for 7 consecutive trading days.
They are gonna liquidate your position, but you will only loose the free margin (300) and preserve the 2700.
However, I don’t see why you would open a standard lot on a $3K account.
Thank you guys, good to know I thought they are going to wipe out all the money I deposit. Is there any other hidden policy I should know order to prevent wipe out my deposit?