Why the same SKU isn't equally profitable everywhere
The same product, at the same or similar sale price, can have meaningfully different true profitability on different marketplaces — because referral fee percentage, fulfillment program cost, ad competition, return rates, and payout timing all vary by platform and category. A SKU that's your best performer on one marketplace can be marginal or unprofitable on another, even at a similar price point.
What actually differs between marketplaces for the same SKU
- Referral/commission fee percentage — varies by category and platform; check each marketplace hub for current rates rather than assuming they're uniform.
- Fulfillment program cost — a size/weight-tiered fulfillment fee (e.g., FBA vs. WFS) rarely matches exactly between platforms for the same product.
- Advertising cost to achieve comparable visibility — a more competitive category on one marketplace can mean a materially higher cost per click or per sale to reach similar visibility.
- Return rate — can differ by platform depending on buyer base and return policy generosity.
- Payout timing and terms — payout frequency affects cash flow, which matters more the tighter your working capital is.
Worked comparison example
Same product, $25 sale price, sold on two marketplaces:
| Line | Marketplace A | Marketplace B |
|---|---|---|
| Sale price | $25.00 | $25.00 |
| Landed cost | $7.00 | $7.00 |
| Referral fee | 15% = $3.75 | 12% = $3.00 |
| Fulfillment cost | $5.50 | $6.75 |
| Ad spend (per-unit average) | $2.00 | $4.25 |
| Return-rate cost (amortized) | $0.40 | $0.90 |
| Contribution margin | $6.35 (25.4%) | $2.10 (8.4%) |
Even though Marketplace B has a lower referral fee percentage, its higher fulfillment cost, more competitive ad landscape, and higher return rate make it dramatically less profitable for this specific SKU. Looking at referral fee alone would have suggested the opposite conclusion.
How to use this to prioritize inventory and effort
- Allocate limited inventory to the higher-contribution-margin channel first, especially under any capacity or storage constraint (see Inventory Management).
- Don't fully abandon a lower-margin channel if it reaches customers you can't get elsewhere, or if the gap is narrow enough that channel diversification's risk-reduction value outweighs the margin difference.
- Re-run the comparison periodically, not just once — fee schedules, ad competition, and return rates all shift over time and can flip which channel is more profitable.
A note on comparing apples to apples
Make sure the comparison uses actual per-marketplace ad spend and return-rate data for that specific SKU on that specific platform — not a company-wide blended average, which will understate the difference between channels (see SKU-Level Profitability Analysis for the same principle applied within a single marketplace).
When the comparison should change a launch decision, not just an allocation one
If a product hasn't launched on a second marketplace yet, run this comparison before committing inventory and listing effort — using your best available fee/fulfillment/ad-cost estimates for the new channel — rather than launching everywhere by default and discovering the economics don't work after inventory is already committed.
Mistakes
- Comparing only the referral fee percentage across marketplaces and ignoring fulfillment, ad, and return-rate differences.
- Using a blended, company-wide ad-spend or return-rate average instead of the actual per-marketplace numbers for that SKU.
- Treating the comparison as a one-time decision instead of revisiting it as fee schedules and competitive dynamics shift.
Checklist
- Referral fee, fulfillment cost, ad spend, and return rate gathered per marketplace for this specific SKU.
- Contribution margin calculated side by side, not just referral fee.
- Inventory/ad-spend allocation decision made based on contribution margin, weighed against total addressable volume per channel.
- Comparison scheduled to be revisited at least twice a year.