Profit and loss calculator
Gross profit is the number people quote. This is the one that reaches your balance, after paying to get in and paying to get out.
Inputs
Result
net = (exit - entry) x size - (entry + exit) x size x fee%.
Two things this leaves out
Slippage, which on a thin book costs more than the fee - check the cross-venue spread on the coin page before assuming your fill. And funding, if the position is a perpetual held overnight; that has its own calculator.