Round-turn cost: adding up what one complete trade charges you

Round-turn cost is what one complete trade charges you: the cost of opening a position plus the cost of closing it, including the costs that are not called fees. A “round turn” is one trade counted as the full circle, in and back out again, which is the only way of counting that tells you what the trade had to earn before you were even.

The phrase matters because almost every published fee figure is quoted per side. When you see a rate attached to a transaction, that rate is being applied once, to one transaction. A trade you intend to close involves two. Reading a per-side figure as if it were the cost of the whole trade halves your estimate of what you pay, and in practice it does worse than that, because commission is usually the smaller half of the total.

Why costs are quoted one side at a time

Venues charge per transaction because that is the unit they actually process. They have no way of knowing, when you open a position, whether you will close it in nine seconds or hold it for a year, or whether you will close it at all. So the fee attaches to the event they can see. The per-side quote is an accounting convention, not an attempt to flatter the number, but the effect on a reader who does not convert it is the same.

The same logic explains the other components. The spread exists because a venue, or the market makers on it, must quote two prices at once: one at which they will buy from you and a slightly worse one at which they will sell to you. You cross that gap when you enter and you cross it again when you exit. Nobody itemises it, because it is not a charge, it is the price. Financing exists because a leveraged position is borrowed exposure and borrowing has a rental cost, charged by the period rather than by the transaction.

Four components, three different billing logics: per transaction, per crossing of the quote, per unit of time held. That is why the total cannot be read off a single line of a fee page.

The four parts of one complete trade

Entry and exit commission are the visible pair. The spread is invisible in the sense that it never appears as a line item, but it is paid in the fill price: you buy a little above the midpoint and sell a little below it. Financing is the component that behaves unlike the others, because it is the only one that keeps growing after you have stopped doing anything.

Working the sum with made-up inputs

Every number below is invented for this example. None of it describes any venue’s actual pricing.

Suppose a venue charges 0.05% per side in commission. Say you open a position worth $4,000 and close it later at roughly the same size.

1. Entry commission: 0.05% of $4,000 = $2.00
2. Exit commission: 0.05% of $4,000 = $2.00
3. Spread: imagine the quoted gap is 0.02% of position value, paid at each end, so 0.04% of $4,000 = $1.60
4. Financing: imagine a charge of 0.01% of position value per eight-hour period, and you hold the position for three such periods: 0.03% of $4,000 = $1.20

Total round-turn cost: $2.00 + $2.00 + $1.60 + $1.20 = $6.80.

Against a $4,000 position that is 0.17% of the position value. The position has to move 0.17% in your favour before the trade is worth exactly nothing, and anything less than that is a loss even if the price went the way you wanted. The headline figure in this invented schedule was 0.05%. The round-turn reality is more than three times it.

Now change one input and leave the rest alone. Hold the same position for nine eight-hour periods instead of three: financing becomes 0.09% of $4,000, or $3.60, and the total goes to $9.20. Nothing about your entry changed. You can run the same structure with your own figures using the crypto fee calculator and the funding rate calculator, and check the result against your intended exit with the profit calculator.

The mistake: treating break-even as the entry price

The specific error is believing you are even when the price returns to where you bought. You are not. At your entry price you are down by the full round-turn cost, because you have paid the entry commission, you will pay the exit commission, you crossed the spread on the way in and will cross it again on the way out, and the financing clock has been running the whole time. Break-even sits a measurable distance above your entry on a long position, and below it on a short.

Two things follow. First, a strategy whose average winning move is smaller than its round-turn cost is a losing strategy regardless of how often it is directionally right, and the fix is either fewer trades or larger moves, not better entries. Second, the cost burden depends on position size when any component is a flat amount: a $4 flat charge against an invented $200 position is 2% of it, and against a $20,000 position it is 0.02% of the same trade structure. Small positions pay disproportionately for flat charges, and only percentage-based schedules scale down cleanly.

The other common slip is netting financing against the direction of the trade. Financing is charged on the exposure, not on the outcome. A position that went nowhere still accrued it, and a position that lost money accrued it on top of the loss.

How to read a fee page after this

Convert before you compare. Take the quoted commission, double it, add two crossings of the spread, then add financing for the number of periods you realistically expect to hold. Express the result as a percentage of position value, because that is the number you can hold against your expected move. Comparing a per-side commission on one venue to a per-side commission on another tells you very little if their spreads or financing conventions differ, and the comparison pages are more useful once you know which total you are comparing. Definitions of each component are in the glossary.

One trade, four charges, three billing logics. Add them up once and the break-even point stops being a guess.

Education only, not financial advice, and trading carries a risk of loss.