Real cost of a trade
The real cost of a trade adds up spread, commission, swap, slippage and any conversion fees. It is what you actually pay to trade.
Many traders only look at the advertised spread. The real cost includes commission, swaps for nights held, slippage on market orders and stops, plus conversion fees if your account currency differs.
Express everything in the same unit, in pips or as a percentage of your risk. A 1.5-pip cost does not weigh the same on a 10-pip stop (15% of the risk) as on a 60-pip stop (2.5%).
Very short-term styles such as scalping are the most sensitive to costs: a small difference per trade can turn a profitable strategy into a losing one.
See also