“Our gross margin is 60%.”

Great. Now tell me your profit margin by SKU after advertising, returns, platform fees, and shipping. Tell me which channel is actually generating profit and which one just looks busy. Tell me what your real margin is on the products you spend the most ad dollars promoting.

Silence. Every time.

This isn’t a dig at founders. It’s a reflection of how most eCommerce financial reporting is set up. It gives you the top-line numbers and hides the detail that actually matters. If you want to know whether your business is genuinely making money, and where it’s making money, you need to track margins differently.

Why Gross Margin Is Not Enough

Gross margin (revenue minus cost of goods sold, divided by revenue) is the number everyone knows. It’s the one your accountant puts in your P&L. And in eCommerce, it’s dangerously incomplete.

Here’s why. Your COGS tells you what you paid for the product. It doesn’t tell you:

• What it cost to acquire the customer who bought it.
• What the platform charged you to process the sale.
• What shipping cost you (or what you subsidised with “free shipping”).
• What percentage of those sales came back as returns.
• What it cost to store that inventory before it sold.

A SKU with a 65% gross margin and a 22% return rate, $15 in ad costs per unit, and Amazon FBA fees is a completely different financial reality than a SKU with a 55% gross margin, a 3% return rate, sold on your own Shopify store with a $4 acquisition cost.

The first SKU might be losing money. The second is almost certainly your best performer. But if you’re only looking at gross margin, they’re nearly identical.

The Margins That Actually Matter

Contribution Margin by SKU

This is the single most important metric most eCommerce brands aren’t tracking.

Take revenue per unit.

Subtract:

• COGS
• Platform/marketplace fees
• Shipping costs (or the net cost after what the customer pays)
• Average advertising cost per unit
• Cost of returns (refunds plus reverse logistics)

What’s left is your contribution margin. This tells you how much each unit actually contributes to covering your fixed costs and generating profit.

Contribution Margin by Channel

The same product can have wildly different margins depending on where you sell it.

• Amazon takes a bigger cut but might have a lower acquisition cost.
• Shopify has lower fees but you’re paying for all the traffic.
• Wholesale has lower margins but zero ad spend and predictable volume.

Until you see margins by channel, you can’t make intelligent allocation decisions.

Customer Acquisition Cost Relative to Margin

Your CAC needs to be viewed in the context of what the customer generates in margin, not just revenue.

Example:

• Average Order Value: $80
• Contribution Margin: 30%
• Actual Margin per Order: $24
• CAC: $25

You’re losing money on the first purchase. That might be acceptable if repeat purchases make up the difference—but you need the data to know.

Net Operating Margin

This includes your fixed costs:

• Team
• Software
• Warehouse overhead
• Professional services

Revenue minus all variable costs minus all fixed costs equals your actual profit.

For most eCommerce brands, a healthy net operating margin sits between 10–20%, depending on category, business model, and growth stage.

How to Get This Data

Most accounting software doesn’t provide this level of reporting out of the box.

Typical approaches include:

• Using A2X to segment revenue and fees by channel.
• Building custom spreadsheet reports.
• Creating BI dashboards that combine accounting, advertising, shipping, and eCommerce platform data.
• Implementing a financial intelligence layer on top of your accounting system.

The important part is ownership.

Bookkeepers record transactions.

A finance leader or eCommerce CFO turns those transactions into actionable margin intelligence.

What to Do With Better Margin Data

Better reporting often reveals opportunities such as:

• 20% of SKUs generating 80% of total profit.
• Products that actually lose money.
• Sales channels that appear successful but are unprofitable after fees and advertising.
• Free shipping policies that reduce profitability.

These insights simply don’t exist in a standard profit and loss statement.

The Bottom Line

Revenue is vanity.

Profit is sanity.

But even total profit can hide what’s really happening inside your business.

The eCommerce brands that scale successfully understand profit margins at the SKU level, by channel, and from sale all the way to the bottom line.

If you can’t measure that today, you’re not behind.

You’re simply missing one of the biggest opportunities to unlock more profit from the business you already have.