Gross margin tells you a product makes money. Net margin tells you the business does. Ecommerce sellers who confuse the two scale themselves straight into a loss.
Gross margin is the percentage of revenue left after the direct cost of the goods sold. It measures the profitability of the product itself, before any of the costs of running the business.
Net margin is the percentage of revenue left after every expense: cost of goods, operating costs, fees, advertising, taxes, and overhead. It measures the profitability of the whole business.
The two answer different questions. Gross margin asks, "Does this product earn more than it costs to acquire?" Net margin asks, "After everything, did the business keep any of it?" A product can pass the first test and the business can still fail the second, which is the defining hazard of ecommerce.
| METRIC | FORMULA | WHAT IT MEASURES |
| Gross profit | Revenue − COGS | Dollars left after product cost |
| Gross margin % | (Revenue − COGS) ÷ Revenue | Product-level profitability |
| Net profit | Revenue − all expenses | Dollars the business keeps |
| Net margin % | Net profit ÷ Revenue | Business-level profitability |
If you sell $100,000 with $60,000 of COGS, your gross profit is $40,000 and your gross margin is 40%. If operating costs, marketplace fees, advertising, and overhead then consume $34,000 of that, your net profit is $6,000 and your net margin is 6%. The product looks healthy. The business is running on fumes. Both numbers are true, and only the second one pays your bills.
In most businesses the gap between gross and net margin is overhead. In ecommerce the gap is a battlefield: marketplace referral fees, FBA fulfillment fees, storage, advertising, software, shipping, and returns. These costs are large, variable, and product-specific, and they sit precisely in the space between gross and net.
That is why an ecommerce seller can post a 40% gross margin and a 3% net margin. The product is fine. The cost of selling it on a marketplace, advertising it to win the buy box, and storing it across fulfillment centers is what closes the gap. The seller who watches only gross margin never sees the squeeze until cash runs short.
A high gross margin invites you to scale. Scaling multiplies the costs in the gap: more ad spend to drive more volume, more storage, more fees. If those costs grow as fast as revenue, scaling grows your top line and your losses together. Net margin is the only number that tells you whether growth is making you money or just making you busy.
You cannot compute either margin honestly without accurate COGS, and you cannot compute net margin without capturing every fee, ad dollar, and overhead cost in the right place. See /glossary/cost-of-goods-sold for how COGS feeds gross margin.
Per-SKU is where it gets actionable. Blended business-wide margins hide the products dragging you down. A per-channel, per-SKU view shows which products earn their keep at the net level and which only look good at the gross level. ConnectBooks applies FIFO COGS per unit and produces per-channel P&L, so you see gross and net margin where decisions actually get made: at the product. For the full walk from gross sales to true net profit on Amazon, see /blog-posts/true-amazon-profitability-after-fees.
| NEXT STEPWatch net margin, not just gross, at the product level. ConnectBooks builds per-channel P\&L with per-unit COGS, starting at $149/mo. See /pricing. |
Gross margin is revenue minus cost of goods sold, as a percentage of revenue, and it measures the product's profitability. Net margin is revenue minus all expenses, including fees, advertising, and overhead, and it measures the whole business's profitability. Gross margin can be strong while net margin is thin or negative.
Because the costs between them, marketplace fees, FBA fees, advertising, storage, software, and shipping, are large in ecommerce. A product can be profitable on its own (high gross margin) while the cost of selling and promoting it on a marketplace consumes most of that profit (low net margin). The gap is where ecommerce businesses succeed or fail.
Both, for different reasons. Gross margin tells you whether a product is worth selling at all. Net margin tells you whether the business is actually keeping money. Watching only gross margin is the classic mistake, because it can stay healthy while net margin collapses under fees and ad spend.
It varies widely by category, price point, and channel mix, so there is no universal target. The more useful discipline is tracking net margin per SKU and per channel over time, so you can see which products and channels are improving and which are eroding, rather than chasing a benchmark number.
Yes, and it happens constantly in ecommerce. A product with a positive gross margin can still lose money once its share of advertising, fees, storage, and returns is attributed. That is why per-SKU net margin matters: it catches the products that look fine on gross margin but drain cash overall.
Clean, accurate books make this manageable. Start a free trial of ConnectBooks to get settlement-level accuracy and real margin visibility for your ecommerce business. No credit card required.
Running an e-commerce business comes with plenty of challenges, but ConnectBooks is here to make your life easier. With real-time insights, seamless integrations, and detailed tracking of your profitability and inventory, you can stay ahead of the game. Whether you’re selling on Amazon, Shopify, Walmart, TikTok or eBay, ConnectBooks helps you manage your finances with 100% accuracy and confidence, so you can focus on growing your business.
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