Lesson 4 of 10
Contribution, the first honest number
After fees, cost of goods and advertising, what is left is what one unit actually leaves behind for the business to run on.
Amazon’s own fees (lesson 2) and landed cost (lesson 3) still don’t finish the walk from revenue to what a unit actually leaves the business. One variable cost remains: what it cost to advertise it. Amazon’s Ads API attributes spend to a specific product and channel, not spread evenly across everything in the account, so it belongs on the same row as the fees and the landed cost it sits beside.
The whole walk, in order
Lesson 1 showed only the two ends of this — revenue, and what was kept. Here is everything between them, in the order Amazon actually takes the money: two fees named in lesson 2, three smaller ones never named until now, landed cost from lesson 3, and advertising, just introduced.
| Step | Amount | Share of revenue |
|---|---|---|
| Revenue | $26,907.89 | 100.0% |
| Referral fee | -$4,316.95 | -16.0% |
| FBA fee | -$4,544.85 | -16.9% |
| Promotions | -$292.43 | -1.1% |
| Refunds | -$403.38 | -1.5% |
| Other fees | -$67.66 | -0.3% |
| Advertising | -$1,531.77 | -5.7% |
| Cost of goods | -$4,219.44 | -15.7% |
| Contribution | $11,531.39 | 42.9% |
It closes: revenue, minus every one of those steps, lands exactly on Contribution at the foot — nothing skipped, nothing counted twice.
Contribution, the first honest number
The Profit page has its own bottom line, Net profit — revenue, less Amazon’s fees, less cost of goods. It stops there because advertising is not split by product on that page. Contribution is what is left once advertising is subtracted too, for one product on one marketplace, which is why it is the first figure in this course honest enough to say what a single row actually earned rather than what the account earned in aggregate. It only stands for rows where every one of those costs — fees, landed cost, advertising — is actually known; a row missing one gets no verdict rather than a guess.
What this walk still cannot see
Every step above scales with a sale — more units, more fees, more landed cost, more advertising. Rent, wages, software and the owner’s own time do not scale that way, and none of them appear anywhere in the walk above: not in an Amazon fee, not in a landed cost, not in an ad bill. They are real costs of running the business all the same, billed to the whole account rather than to any one product, which is exactly why Contribution being positive is not the same question as whether it was enough. That question is where the next lesson picks up.