Manage Contribution Margin, Not ACoS

Most Amazon reporting that reaches a headquarters in Asia contains revenue, advertising spend and an efficiency ratio. It is an easy report to produce and an easy one to read. It is also, on its own, close to useless for deciding anything.

The problem is not the ratio. The problem is what the ratio omits.

What an efficiency target hides

An advertising cost-of-sale target treats advertising as the only variable cost that matters. In a European marketplace business it is usually not even the largest one. Between the price a buyer pays and what the business keeps sit referral fees, fulfilment fees, storage, VAT, returns and their disposition, inbound freight, duty and the landed cost of the unit itself.

Two products can hit the same advertising efficiency target and have entirely different economics. One contributes; the other consumes cash while looking like growth. A report built on revenue and ad ratio cannot tell them apart — and neither can anyone reading it.

It gets worse as the account grows, because the natural response to a good ratio is to spend more behind it. If the underlying contribution is thin, scaling the product scales the loss.

What to measure instead

Contribution margin per unit, per marketplace. Selling price, less landed cost, less all marketplace fees, less the realistic return cost for that product in that market, less the advertising attributable to it. That is the number that tells you whether a product should be pushed, repriced, restructured or discontinued.

Contribution after advertising, by product. Not blended. Blending hides the products that are being subsidised by the rest of the range — often indefinitely, because nobody can see them.

Organic share of revenue. If paid share is rising while total revenue rises, the business is becoming more expensive to run, not healthier. This one trend line explains more stalled European accounts than any other.

Return rate by product and market. Returns vary enough by category and market to move contribution by several points. Modelled at a European average, they will be materially wrong somewhere.

Inventory cost of holding position. Rank has to be defended, and defending it has an inventory cost. A product with thin contribution and high replenishment requirements can be a worse use of capital than a lower-revenue product with stronger margin.

This is not an argument against efficiency targets

Efficiency ratios are useful operationally. They are a fast signal, they are easy to steer against day to day, and campaign-level decisions need something faster than a full margin calculation.

The point is that they are an operating proxy, not an objective. The objective is contribution margin. When the proxy is treated as the objective, three predictable things happen: spend gets cut on products where advertising was actually profitable, spend gets increased on products where it was not, and price gets used as the lever of last resort on products whose real problem was cost structure or conversion.

The practical implication for cross-border brands

For a brand operating Europe from Asia, this is primarily a visibility problem. The data needed to calculate contribution — landed cost, freight, duty, the fee structure of each marketplace, actual return behaviour — sits in several places, some of them inside the company rather than inside Amazon. Assembling it is unglamorous work that nobody owns by default.

Until that work is done, every European growth decision is being made on revenue. That is a manageable state of affairs at a small scale. It stops being manageable at exactly the point where the business starts to matter.