If you ask a casual crypto trader what their profit is, they'll usually subtract the buy price from the sell price and call it a day. That number is almost always wrong — sometimes by 30% or more once exchange fees, network gas, slippage, funding rates, and tax are included. After reviewing thousands of trade logs, I keep seeing the same seven mistakes that quietly destroy returns. This guide walks through the right way to calculate crypto profit, with worked examples for spot, leveraged, staking, and DCA strategies — and a free calculator at every step.