Revenue and unit-sales rank are misleading on their own — a top-selling SKU can be your least profitable one once fees, fulfillment, and ad spend are attributed correctly.
How to run the analysis
For every SKU, calculate contribution margin (see Gross vs. Contribution vs. Net Margin) using its actual fees, actual fulfillment cost (size/weight-specific, not a blended average), and its actual attributed ad spend — not a company-wide average, which hides SKU-level problems. Use the Product Profitability Calculator per SKU, or build this into a standing spreadsheet/BI process if your catalog is large.
A worked example: ranking by revenue vs. by contribution margin
| SKU | Monthly revenue | Revenue rank | Contribution margin % | Contribution margin $ | CM rank |
|---|---|---|---|---|---|
| A | $18,000 | 1 | 8% | $1,440 | 4 |
| B | $12,500 | 2 | 34% | $4,250 | 1 |
| C | $9,800 | 3 | 22% | $2,156 | 2 |
| D | $6,200 | 4 | 28% | $1,736 | 3 |
SKU A is the clear revenue leader but ranks last in actual dollars of contribution margin generated — it's consuming inventory capital, fulfillment capacity, and likely a large share of ad spend to produce the least real profit of the four. Without this analysis, a revenue-only view would have you doubling down on exactly the wrong SKU.
What to look for
- High-revenue, low-or-negative-contribution SKUs — often the most urgent to fix or discontinue, since they're consuming operational attention disproportionate to the profit they generate.
- SKUs where ad spend is propping up otherwise-unprofitable economics — a SKU that's only "working" because of heavy advertising is fragile to any ad-cost increase or algorithm change. Check what contribution margin looks like with ad spend backed out — if it's still thin or negative, the SKU has a structural problem, not just an advertising-efficiency problem.
- High-return-rate SKUs quietly eating margin — a product with an above-average return rate can look profitable in a simple margin calculation that ignores returns.
- SKUs with a large gap between gross margin and contribution margin — this signals the SKU is unusually fee-, fulfillment-, or ad-cost-heavy relative to its price point, worth investigating even if the absolute contribution margin looks acceptable today.
What to do with what you find
Options in rough order of effort: reprice, renegotiate sourcing cost, reduce ad spend and accept lower volume, or discontinue (see SKU Rationalization) if none of the above gets the SKU to an acceptable contribution margin.
How often to run this
For a catalog under active management, a quarterly full pass plus a lighter monthly check on your top 10-20 SKUs by revenue catches problems before they compound across a full quarter of ad spend and inventory decisions.
Troubleshooting
- Symptom: a SKU's contribution margin swung sharply from last quarter with no obvious cause. Check for a fee-schedule change on the marketplace, a freight-cost or supplier-price change, or an ad-cost shift in a more competitive category — the swing is a real signal, but the cause is usually one specific input, not a mystery.
- Symptom: the analysis shows almost every SKU is barely profitable. This usually points to a structural issue (pricing set too low across the board, an outdated cost assumption baked into every SKU's model, or a fee schedule that changed and wasn't updated) rather than 10-20 unrelated individual SKU problems — check your underlying cost assumptions before assuming every product needs individual attention.
Best practices
- Use each SKU's actual attributed ad spend and return rate, not a blended company average.
- Re-run the full pass on a fixed schedule (quarterly at minimum) rather than only when something already feels wrong.
- Rank by contribution margin dollars, not just percentage — a lower-percentage, higher-volume SKU can generate more total profit than a high-percentage, low-volume one, and both views matter.
Mistakes
- Ranking SKUs by revenue or unit sales alone and never calculating contribution margin at all.
- Using a blended average ad-spend or return-rate figure across all SKUs, which hides exactly the SKUs the analysis is meant to find.
- Finding a money-losing SKU and doing nothing about it because it "still generates revenue" — revenue without contribution margin doesn't fund the business.
Checklist
- Contribution margin calculated per SKU using actual (not blended) fee, fulfillment, ad-spend, and return-rate data.
- SKUs ranked by contribution margin dollars and by contribution margin percentage separately.
- High-revenue, low-contribution SKUs flagged for a pricing, sourcing, ad-spend, or discontinuation decision.
- Next full pass scheduled (quarterly recommended).