Here's the math that sinks more Shopify brands than any other: the product costs you $6, you sell it for $30, so you're making $24 a unit — a tidy 80% margin. Except you're not. By the time that unit actually reaches a customer and stays with them, a large share of that $24 is gone, spent on costs that never show up in your "cost of goods." If you price, discount, and scale ad spend off the COGS number, you're flying on an instrument that's lying to you.
The Costs Hiding Behind COGS
Your true, fully-loaded cost per unit stacks up like this:
- Product cost (COGS). The $6. The only number most founders track.
- Inbound freight and duty. Getting it from the factory to your warehouse or 3PL — and if it's imported, duty on top. Real money per unit, especially at small volumes.
- Fulfillment. Your 3PL's pick-pack fee, plus monthly storage. Call it $2–4 a unit before anything ships.
- Outbound shipping. What it costs to get the box to the customer — or, if you offer "free shipping," the amount you're eating.
- Payment processing. Roughly 2.9% + 30¢ per order. On a $30 order, about a dollar.
- Returns. The refund, the return shipping, the unit you often can't resell, and the labor to process it. In some categories this runs 5–10% of revenue.
- Customer acquisition cost (CAC). The biggest and most ignored. If it costs $12 in ads to land the order, it belongs in the per-unit math as surely as the product does.
Gross Margin vs. Contribution Margin
Gross margin (price minus COGS) is the number that makes you feel rich. Contribution margin — what's left after all the variable costs above — is the number that pays your rent. On our example, a $30 product might carry a 50–65% gross margin and a 15–25% contribution margin once fulfillment, shipping, fees, returns, and CAC come out. That contribution number is what actually funds overhead and profit. It's the one to run the business on.
Three Places the Lie Does the Most Damage
- Pricing. Set price against COGS and you leave no room for the other costs, then wonder why growth doesn't create cash.
- Discounting. A "20% off" promo on an 80% gross margin feels harmless. Against a 20% contribution margin, that discount can wipe out the profit on the order entirely.
- Ad spend. Scaling paid acquisition only works if contribution margin exceeds CAC. Founders who track gross margin scale spend confidently into per-unit economics that were already underwater.
The Free-Shipping Subsidy
"Free shipping" is never free — it's a cost you've chosen to absorb instead of the customer. That's a legitimate strategy, but only if it's in your per-unit number. Baking $5 of shipping into a product you priced off a $6 COGS is how a growing brand runs out of cash while the top line looks great.
Build the Real Number Before You Scale
Before you pour money into ads or a big reorder, build the one-unit P&L: start at price, subtract every line above, and look at what's actually left. That contribution figure tells you your true margin, your real discounting room, and the CAC you can actually afford. It's the DTC version of landed cost — and the brands that know it to the penny are the ones that survive their own growth.
The brands that scale profitably aren't the ones with the best product cost — they're the ones who know their fully-loaded cost per unit and price, discount, and buy ads against that number, not the flattering one.
Do you have a per-unit number that includes fulfillment, shipping, fees, returns, and CAC — or are you working off product cost and a spreadsheet? We'd like to hear how you track true unit economics.