Seller guide
How do I compare net margin across Amazon, Walmart, and eBay?
Put one SKU's channel economics on a comparable basis: percentage fees, fulfillment, shipping, variable costs, allocated fixed costs, observed volume, and price gaps.
Start with the same product cost and comparable periods
Use one verified landed product cost for the same SKU, then choose channel periods that cover the same dates or clearly label the difference. Revenue alone is not comparable when one channel sold more units, charged a different price, or absorbed shipping. Keep units as observations, not forecasts.
Build each channel's complete supplied cost stack
For each channel, record price, percentage fees, fixed per-order fees, fulfillment, outbound shipping, and other variable costs. Divide only genuine period fixed costs by that channel's observed units. Do not import a fee percentage from another category or assume that fulfillment and returns cost the same across marketplaces.
Compare contribution per unit before period totals
Contribution per unit is price less product cost and every supplied channel cost. Divide it by price for contribution-margin percentage, then multiply by observed units for period contribution. Ranking by margin shows economic efficiency; period contribution shows scale. A high-margin small channel and a lower-margin large channel can both be valuable for different reasons.
Separate price alignment from margin alignment
Equal sticker prices do not create equal margins when fee rates and fulfillment costs differ. Solve the price each channel would need to match a chosen baseline margin, then treat that number as a scenario—not a recommendation. A price-parity gap, seller floor, or supplied MAP reference is a review flag, not proof of a legal obligation or permission to change the offer.
Act only after checking live fees and governing terms
Reconcile the arithmetic with current seller statements, return costs, storage, ads, taxes, discounts, and contract terms. If one channel remains negative after the complete stack is entered, review price, cost, fulfillment, and assortment options with the responsible human. Never synchronize prices from a planning worksheet without account-level review.
Tools that help with this
- Multi-Channel Net-Margin Parity Checker ($0.50) — Rank supplied channel margins and solve baseline-margin what-if prices
- Marketplace Price Change Break-Even Analyzer ($0.25) — Test candidate prices against one channel's contribution and break-even volume
- Amazon FBA vs FBM Cost Comparison Worksheet ($0.50) — Separate Amazon fulfillment-mode economics before comparing channels
Every paid output is a draft for your review before you publish, appeal, or activate anything. Friday does not access your seller account.