Contribution margin by SKU is the metric that tells you whether a marketplace product is actually paying its way. Revenue cannot do that. ROAS cannot do that. Even gross margin gets a bit too optimistic after marketplace fees, returns and advertising join the party.
Use this how-to with contribution margin, profit analytics, Amazon P&L, ACOS, TACoS vs ROAS, marketplace analytics and ad budget guardrails.
Step 1: Export order revenue by SKU
Start with net item revenue by marketplace and SKU. Remove VAT/sales tax where relevant and separate coupons, discounts, shipping income and refunds. Use order date and settlement date consistently. Mixing them is how dashboards become modern art.
gross_item_revenue
- tax
- coupons_and_discounts
- refunds
= net_revenueStep 2: Add product and marketplace costs
Add COGS, marketplace commission, referral fees, fulfillment, pick-pack, storage, payment fees and any channel-specific cost. For Amazon, include FBA or fulfillment costs. For bol, include LVB where relevant. For TikTok Shop, include platform and creator commission.
Step 3: Add expected returns
Calculate return cost by SKU using actual return rate, refund amount, return shipping, handling and damaged-stock markdowns. If return data lags, use a rolling expected return rate and update it weekly.
Step 4: Allocate ad spend
Where possible, connect ad spend directly to advertised SKU. When campaigns cover multiple products, allocate spend by attributed sales, clicks, impressions or a predefined campaign role. Document the method. Future-you deserves nice things.
pre_ad_contribution = net_revenue - cogs - marketplace_fees - fulfillment - expected_return_cost
post_ad_contribution = pre_ad_contribution - allocated_ad_spend
contribution_margin_pct = post_ad_contribution / net_revenueStep 5: Create decision bands
| Band | Margin signal | Action |
|---|---|---|
| Scale | Healthy positive margin | Increase ads or stock carefully |
| Fix | Positive before ads, weak after ads | Adjust bids, price or campaigns |
| Protect | Good margin, low stock | Cap ads and reorder |
| Stop | Negative after variable costs | Pause ads, reprice or delist |
Step 6: Verify the calculation
Compare total calculated contribution against finance totals. Check a sample of orders manually. Reconcile marketplace payouts. Confirm ad spend allocation does not double-count Sponsored Products, display or creator boosts.
Common pitfalls
- Using gross revenue instead of net revenue.
- Forgetting coupons, refunds or payment fees.
- Applying one blended return rate to every SKU.
- Letting ad spend sit at campaign level.
- Ignoring stockouts and pricing changes when interpreting margin.
What to check every week
- Top negative-margin SKUs by absolute loss.
- High-revenue SKUs with low contribution margin.
- Campaigns that push profitable SKUs below margin floor.
- Return-rate changes by SKU and marketplace.
- Stock cover for profitable advertised products.
How FiveX helps
FiveX connects marketplace orders, fees, returns, ad spend, stock and product costs into SKU-level profit views. You get contribution margin without rebuilding the same spreadsheet until it develops its own personality.
FAQ
What is SKU contribution margin?
It is the profit a SKU keeps after variable costs such as COGS, marketplace fees, fulfillment, returns, coupons and ad spend.
Should ad spend be included?
Yes for post-ad contribution margin. Also keep a pre-ad view to understand how much advertising pressure the SKU can carry.
How do returns affect contribution margin?
Returns reduce net revenue and add costs such as shipping, handling, refunds and damaged-stock markdowns.
How often should this be calculated?
Weekly for active marketplace teams, daily during peak trading periods or major campaign pushes.
Can FiveX automate this?
Yes. FiveX connects marketplace, advertising, fee, stock and cost data so SKU contribution margin is available in one workflow.