In any open trades you have you will see the profit or loss listed, which is the real-time mark to market value of the trade. You can close the trade at any time and this is the profit or loss you can expect. However, you might want to know at what value you will make ‘x’ amount of profit, and for that you need a forex calculator (unless you want to do the calculations by hand). In honesty the calculation itself is quite straightforward as it is simply the position size multiplied by the number of pips movement in the position. So, if you want to know how much profit (or loss) comes from a 20 pip move you can easily do so with the forex calculator. It will even calculate the value of each pip in those pairs where the USD is not the quote currency.