Round-trip cost
The full cost of entering and exiting a position: spread, commission, swap and expected slippage. Measure it in a fraction of R, before judging a strategy.
Definition
The round-trip cost is the total price of completing a trade — entry and exit. It consists of the spread (bid–ask), commission, any swap (overnight charge) and expected slippage (the difference between the price you clicked and the fill). The same setup costs different amounts on different products; you measure this cost as a fraction of your 1R, not “by eye”.
Example
An index CFD: a 2-point spread + 3 PLN commission + 1.5 PLN swap per night. If your 1R is 20 PLN, the spread and commission alone come to roughly 0.25–0.35R per round trip — significant with frequent entries, lethal when scalping.
Anti-example / common mistake
Judging a strategy “from the chart” without counting the cost of entry and exit. If the cost is 0.5R or more per trade, at least every second transaction only works to cover costs — that is not a shortage of signals, it is an instrument that is too expensive or entries that are too frequent.