差价合约交易的全部成本：从点差到滑点

Ask what a CFD trade costs and you will usually be shown one number: the spread. It is the most visible cost, and on a liquid pair it looks reassuringly small. But a position's true cost has four parts (spread, commission, overnight financing, and slippage), and they arrive on different schedules, with very different visibility. This article works all four through a single trade, in currency rather than jargon, so you can see where the money actually goes.

The worked example throughout: one standard lot of EUR/USD, €100,000 of notional exposure, bought at 1.0900 and held through five nightly rollovers. The price is picked for clean arithmetic, not quoted from anywhere. At that price the notional is about $109,000, and one pip (0.0001) is worth $10 per lot. Every cost below is converted into dollars on that same trade, because pips only mean anything once they become currency.

The spread: from pips to currency

The spread is the gap between the price you can buy at and the price you can sell at. You cross it once per round trip (buy at the ask, sell at the bid), so it is charged in full the moment you enter. On a spread-only account quoting EUR/USD at 1.2 pips, the arithmetic is short: 1.2 pips × $10 per pip = $12 on one lot. Your platform shows the effect immediately: open the position and it starts roughly $12 underwater before the market has moved at all.

Two properties make the spread easy to underestimate. It scales with trading frequency, not holding period — ten round trips cost ten spreads. And it is not constant: quoted spreads widen around scheduled news, at the daily rollover, and in the thinner hours of the day, because the market's depth is not uniform around the clock. The same pair can cost a multiple of its headline spread at the wrong hour.

Commission and the raw-spread account

Account styles split the same cost differently. One style quotes a wider all-in spread and no commission; the other quotes a near-raw spread and charges an explicit commission per lot, per side. Suppose the raw-spread account shows EUR/USD at 0.2 pips and charges $3.50 per lot per side. The entry-and-exit cost is then 0.2 pips × $10 = $2 of spread, plus 2 × $3.50 = $7 of commission: $9 all-in.

That is the honest way to compare the two styles: convert everything into one round-trip figure. Here $9 beats $12, but the ranking is not a law: it depends entirely on the two schedules, and at other spreads and commission tiers it flips. What the commission has in its favour is legibility: it appears as a visible line on your statement at a published rate. The all-in spread does the same work while looking like nothing happened.

Overnight financing: the cost of staying

A CFD gives you leveraged exposure without owning the underlying, and keeping that exposure open past the daily rollover incurs financing, the charge usually called swap. For an FX pair the nightly amount is driven by the short-term interest-rate differential between the two currencies, adjusted by the broker's markup. The formula has a recognisable shape: notional × (rate differential ± markup) ÷ 360 or 365, depending on the day-count convention; equivalently, a published swap-points figure × pip value × lots. Depending on which currency you are long, the differential itself can work for you or against you; the markup drags both directions towards cost.

Suppose the schedule works out to −$6.50 per night on our long one-lot position. That figure is made up; the real one comes from your broker's published swap schedule and moves with central-bank rates. Five rollovers are not necessarily five charges. Spot FX settles two business days after the trade, so brokers book a triple rollover one day a week (conventionally Wednesday) to carry the weekend. If our five nights include that day, we are charged for seven: 7 × $6.50 = $45.50. On this trade, the line item almost nobody watches is larger than spread and commission combined. The full mechanics, including why the sign flips between pairs, are their own article.

The spread is the price of getting in. Financing is the price of staying.

Slippage is a distribution, not a fee

Slippage is the difference between the price you requested and the price you were filled at. It is the one cost with no schedule, because it is not a fee at all — it is a distribution. Many fills land at the requested price; some land worse; under some execution models a few land better. The width of that distribution depends on your order size and type, on volatility at the moment of execution, and on how much liquidity is resting in the book when your order arrives.

EUR/USD sits inside the deepest market there is: global FX turnover averaged $9.6 trillion per day in April 2025, with the US dollar on one side of 89.2% of all trades ¹. That depth keeps typical slippage on modest retail sizes small in normal hours. But depth is a time-of-day phenomenon, and it evaporates around scheduled news. A stop-loss becomes a market order once triggered: in a fast market it fills where the liquidity is, not where your level was.

Global FX turnover, April 2025

$9.6tn/day^†

Trades with USD on one side

89.2%^†

Retail leverage cap, major FX pairs

30:1^†

Because slippage is a distribution, the only honest estimate is your own data: log requested price against filled price for every order and look at the median and the tail, order type by order type. For planning a single trade, a budget figure stands in for that log. We will pencil in 0.1 pips per side ($2 per round trip) purely as a placeholder for numbers you should eventually measure yourself.

The effective round-trip cost

Now add the column. On the raw-spread account, the five-night trade costs $2 spread + $7 commission + $45.50 financing + $2 slippage budget = $56.50, about 5.7 pips. On the spread-only account: $12 + $45.50 + $2 = $59.50, about 6 pips. That total is the effective round-trip cost, the favourable move the position must produce before it has earned anything. Against roughly $109,000 of notional it is a modest-sounding 0.05%. But you did not post $109,000.

Under the 30:1 retail leverage cap for major pairs, set by ESMA's 2018 product intervention measures ² and made permanent for the UK by the FCA from August 2019 ³, the margin on this position is about $3,633. Measured against the money actually committed, the ≈$57 round-trip cost is roughly 1.6%. Same trade, same arithmetic: costs are charged on notional and felt on margin. That asymmetry is a large part of what the standardised loss warnings are pointing at.

None of this is meant to be secret. Under MiFID II, EU-regulated firms must aggregate the costs and charges of both the service and the instrument, express the total as a cash amount and as a percentage, provide it ex-post at least annually, and supply an itemised breakdown when a client asks for one ⁴. If you trade CFDs with an EU broker, that statement exists. Read it, and check it against your own log.

The four costs are not equally visible, and visibility has nothing to do with size. In this example the cost everyone watches, the spread, was the second-smallest number on the page, and the cost that accrues silently, financing, was the largest. Shorten the holding period to a day and the ranking inverts: financing drops to zero and the spread dominates a scalper's economics. There is no universal ranking, only the habit of converting all four into currency, for your trade, before you place it.