Profit In foreign exchange is the difference between your open and close price. When trading forex, you can open a trade in 2 directions: buy (long) and sell (short). To make a profit with a buy trade, you need to buy a currency at a low price and sell at a higher price. To make a profit with a sell trade, you need to sell a currency at a high price and buy it back at a lower price. For example, using our calculator as a gold profit calculator, if you buy 100 units (standard lot of gold) of gold at $1890.00 and sell it at $1891.00, you would profit $100.