Your gross margin is lying to you

This is a post in our series on Financial Mastery for eCom Owners, specifically Commandment #2: Master Your Financial Statements.

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Two products. Same price. One has a gross margin of 65%, the other 50%.

Which one do you push harder?

If you said a product with a 65% margin, you might be leaving some serious money on the table. I’ve watched store owners make this mistake time and time again—prioritizing products, killing campaigns, and allocating resources based on a number that doesn’t tell the whole story.

Gross margin is one of the most watched metrics in eCommerce. It is also one of the most misleading.

What does gross margin actually tell you?

Gross margin tells you how much it costs to manufacture your product and deliver it to your warehouse.

That’s all.

It does not take into account the cost of acquiring a customer. Ignores shipping and packaging. It skips credit card fees, returns, and all the other variable costs of actually selling and delivering that product to the customer.

So when you look at your P&L and see a healthy gross margin, you’re seeing an incomplete picture. Your income statement gives you one big average across all products and all channels—and that average hides the truth about what’s actually making you money.

The metric that really matters

The contribution margin tells you what is left over after ALL variable costs are paid. It answers the question, “When I sell this product, how much does it actually go to cover my overhead and generate a profit?

This is the number that should guide your decision.

I’ll show you why with a real-life example.

Example Steel bells

Kavon Khoozani runs Bells of Steel, a fantastic home gym equipment company. Let’s pretend we’re looking over his shoulder and deciding which products to push more. (These numbers are hypothetical for illustration purposes.)

It sells two products for $400 each:

Product A: Weight bench

• Gross margin: 65%
• Looks great on paper

Product B: Top Barbell

• Gross margin: 50%
• He looks worse

Easy call, right? Push the bench.

Not so fast.

When we calculate the contribution margin – factoring in shipping costs, ad complexity and conversion factors – the picture turns:

Weight bench:

• Higher shipping costs (bulky goods)
• More complex advertising is required
• Harder customer conversion
• Contribution margin: 30%
• Kavon keeps: $120

Dumbbell:

• Ships cheaper
• Simple dirty
• Easier customer acquisition
• Contribution margin: 40%
• Kavon keeps: $160

The “worse margin” product puts $40 more in his pocket with every single sale.

Multiply that by thousands of orders and you start to see how optimizing for gross margin can quietly cost you a fortune.

Why it ruins your discount math

The same blind spot forces store owners to wildly underestimate how much the discount actually costs.

Let’s say you sell podcast gloves for $100. (Yes, podcast gloves. Every serious podcaster needs proper hand tightening.)

You have 80% gross margin. Fat and healthy. So you think running 20% ​​off is no big deal – you’re only giving up a quarter of your profit, right?

Poorly. Very wrong.

Here’s the real math:

Your gross margin is 80%, but after factoring in customer acquisition, shipping, packaging, and credit card fees, your contribution margin is 40%. That means $40 per sale goes to overhead and profit.

You now have a 20% discount.

You cut your actual profit in half with a “small” 20% discount.

This $20 discount will not come out of your gross margin. It comes directly from your contribution margin.

$40 turns into $20.

You cut your actual profit in half with a “small” 20% discount.

And that’s assuming your other variable costs stay the same. If you spent more on sales promotion ads? Even worse.

Why Black Friday Feels Like a Treadmill

This is why so many store owners feel drained after big promotional periods.

Record revenues. Order record. Record hours worked. And somehow… not that much more profit to show.

The math is brutal when you don’t understand the contribution margin. You work harder to sell more units at dramatically reduced real margins.

How to calculate your contribution margin

The contribution margin is not shown on your income statement. You will have to calculate it yourself, usually in a table.

Here is the basic formula:

Contribution margin = selling price – variable costs

Variable costs include:

• Cost of goods sold
• Cost of customer acquisition (for this product/channel – estimates if you have to)
• Shipping and packing
• Credit card processing fees
• Estimate returns and refunds (some products will return much more than others)
• Any additional costs that increase with each sale

Your assignment this week

Calculate the contribution margin for:

• your top 10-20% of products (the ones that bring in the majority of your sales)
• Your top 2-3 sales channels

You’ll probably be surprised at what you find. Products you thought were winners may fall short. The channels you’ve been neglecting may be your most profitable.

And the next time you’re planning a promotion, you’ll know the true cost before you commit.

Want to go deeper?

Are you interested in regular financial championship information from the archives of our 7- and 8-figure owner community?

Or do you want detailed resources, templates and guides on how to accurately calculate contribution margin in your business? If so, let’s stay in touch