Swap costs on positions held for multiple days can genuinely erode a trade that looks profitable on price movement alone and most traders do not factor this in thoroughly enough until it starts showing up on their statements. The calculation depends on the pair, the direction, the lot size, and the number of nights held and doing it manually every time is tedious and error prone. https://roboforex.com/beginners/start/profit-and-loss-calculator/forex/ includes swap in its calculation output which means I can see the net position including financing cost rather than just the gross pip profit and that complete picture is what I actually need when deciding whether a swing trade over several days is worth holding.