Forex Margin Calculator

Work out how much margin you need to open a leveraged forex position. Enter your lot size, the pair price and your leverage, then press Calculate.

Written by TopicDrill Editorial Team·Updated June 2026

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How the forex margin calculator works

Margin is the deposit your broker locks up while a leveraged trade is open. It is not a fee. It is collateral that is returned once you close the position. The calculator takes the full value of your trade, the notional value, and divides it by your leverage to show exactly how much of your own money is tied up.

The notional value is the number of units you trade multiplied by the current price. One standard lot is 100,000 units, so a EUR/USD position of one lot at a price of 1.0850 has a notional value of about $108,500. With 100:1 leverage you only need roughly $1,085 of margin to open it.

A quick example

Suppose you want to buy two standard lots of a pair trading at 1.25 with 50:1 leverage. The notional value is 200,000 units times 1.25, or $250,000. Divide by 50 and the required margin is $5,000. Lower the leverage to 20:1 and the same trade needs $12,500.

Things to keep in mind

This tool assumes your account currency matches the quote currency of the pair, which is the common case for USD pairs. Always leave a buffer of free margin so a normal price swing does not trigger a margin call. For an overview of the risks of margin trading, see the U.S. Securities and Exchange Commission investor site. You can also size positions with our other free calculators.

Frequently asked questions

How is forex margin calculated?

Required margin equals the notional value of the trade divided by your leverage. The notional value is the lot size times the contract size times the current price. For example, one standard lot of EUR/USD at 1.0850 with 100:1 leverage needs about $1,085 in margin.

What is leverage in forex?

Leverage lets you control a large position with a small deposit. With 100:1 leverage you put up 1% of the position value as margin and borrow the rest from your broker. Higher leverage means less margin, but it also magnifies both gains and losses.

What is a standard lot?

A standard lot is 100,000 units of the base currency. A mini lot is 10,000 units and a micro lot is 1,000 units. Set the contract size field to match the lot type you trade so the margin figure is accurate.

Does margin change if the price moves?

Yes. Required margin is based on the current price, so as the pair moves the margin needed to open a new position shifts slightly. Once a trade is open, brokers also track your used and free margin against a margin call level.

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