Why break-even is not the entry price
A position opened at 50 and closed at 50 does not come out even. Two commissions have been charged, one on the way in and one on the way out. Each fill landed a little away from the price on the screen, and the two orders sat on opposite sides of the spread. All of it is owed whatever the market did in between, so the level where a trade stops costing money sits above the entry when long and below it when short.
This page works out where that level sits, in both directions. The first mode takes the entry, the size and the costs, and returns the price at which the position is exactly flat, and how far that is in percentage and in price. The second takes an exit price as well, and returns what is left of the move once the same costs are paid. The arithmetic is identical; only the known end changes.
Why a fixed fee lands hardest on small positions
A commission quoted as a percentage scales with the position: it takes the same share of a 200 ticket as of a 20,000 one, and moves the break-even level the same percentage in both. A fixed fee behaves in the opposite way. It is the same money whichever size it is charged on, so as a share of the position it shrinks as the position grows. The table above holds one cost structure still and varies only the size: the smallest ticket needs a move roughly six times larger than the largest.
It does not follow that positions ought to be larger. How much of an account a single idea may put at stake is decided by the distance to the stop and the risk budget, not by a fee schedule, and our position size calculator works that out from the account as it stands. What does follow is that a round trip has to be read as a percentage of the position it is charged on, not as an amount.
The same cost, paid more often
A cost that reads as negligible on one trade is a different matter across two hundred. A round trip taking 0.4% of the position takes it every time that position is opened and closed, so a plan turning its capital over once a week hands across roughly twenty per cent of the position value in a year, in costs alone. Trading the same idea less often does not make one round trip cheaper; it reduces how many there are to pay for.
That is why frequency belongs in the same conversation as costs. A system with a small average gain per trade can look profitable on the raw numbers and still finish behind once each of those trades has paid its way in and out. The way to tell is to subtract the cost of a round trip from the average trade rather than from the winners, and our expectancy calculator produces that average across a series of trades.
The cost nobody itemises
Commission arrives on the statement with a number next to it. The spread does not. It is paid at the moment of the fill, in the gap between the price a buyer pays and the price a seller receives, and no line item records it. On a liquid instrument held for weeks it is small enough to leave out of the sum. On a thin one, or on a position opened and closed inside the same session, it can outweigh the commission it sits behind, and it is charged per unit rather than per order.
Slippage works the same way and is harder to pin down, since it depends on the order book at the moment the order arrives rather than on a published schedule. Both fields stay optional and count as zero while blank, the honest default for anyone who has not measured them. Where the stop and the target then sit relative to that level is a separate decision, and our risk / reward calculator handles the distances between them.
How to read each number
The headline is the break-even price in the first mode and what is left of the move in the second. Move needed restates the distance from entry to that level, once as a percentage and once in the units of the instrument itself. Cost of the round trip adds both commissions, both sides of any fixed fee, and the spread and slippage across every unit held. Cost per unit divides that total by the size, worth holding next to a typical daily range. In the second mode, the result before costs is the raw move in money, and the share of the gross says how much of it the costs took.
