How To Calculate True Product Profitability in Ecommerce
The Short Answer
True profit per unit = Price − COGS − Shipping − Platform Fee − Ad Cost Per Unit. That is the only version that matters if you want to know whether a product really makes money. Most sellers stop one line too early. They know product cost. They sometimes know shipping. They often ignore platform fees and almost always treat ad spend as a separate budget instead of a per-unit cost. That shortcut is what makes a product look healthy in a spreadsheet while cash flow says the opposite. Calculate gross profit first, then divide ad spend by units sold to get net profit per unit. If the product cannot clear a solid net margin after those steps, it is not ready to scale.
When To Use This
- Before placing the first inventory order for a new product.
- When a supplier offers a lower quoted COGS and you need to see whether the margin improvement is meaningful.
- Before launching paid ads so you know whether the unit economics can support acquisition.
- During monthly SKU reviews when deciding which products deserve more budget and which should be cut.
Step-By-Step: A Real Example
Take a beauty brand selling a face serum on Shopify. The product sells for €35. COGS is €10.50. Shipping to the customer averages €4. Monthly ad spend is €300. Monthly unit sales are 60.
Start with the platform fee because this is where many product-profit calculations quietly break. Shopify Basic payment processing is 2.9% + €0.30 per transaction. On a €35 sale, the fee is:
35 × 0.029 + 0.30 = €1.315
Round that to €1.32. That is not a rounding detail. It is a real per-order cost that comes out of every transaction before the business sees the payout.
Now calculate gross profit per unit:
Gross Profit = Price − COGS − Shipping − Platform Fee
Gross Profit = 35 − 10.50 − 4.00 − 1.32 = €19.18
This tells you what is left before acquisition cost. Next convert that number into gross margin:
Gross Margin = 19.18 ÷ 35 = 54.8%
At this point the product looks strong. Many sellers stop here and call it profitable. That is still incomplete because the brand spent money to generate the sale.
Now spread ad spend across units sold:
Ad Cost Per Unit = 300 ÷ 60 = €5.00
This is why ad spend must be assigned to each unit instead of being treated as vague overhead. The product had to absorb €5 of acquisition cost to produce each sale during that month.
Now calculate net profit per unit:
Net Profit = Gross Profit − Ad Cost Per Unit
Net Profit = 19.18 − 5.00 = €14.18
Then calculate net margin:
Net Margin = 14.18 ÷ 35 = 40.5%
Finally scale that out to monthly profit:
Monthly Profit = 14.18 × 60 = €850.80
This is the number that tells you whether the product actually makes money after the cost of getting the customer.
Now compare exactly the same product on Amazon FBA. Amazon's fee reference here is 15% referral fee + €3.50 FBA fulfillment fee. On a €35 product the platform cost becomes:
Amazon Fee = 35 × 0.15 + 3.50 = €8.75
Recalculate gross profit:
Gross Profit = 35 − 10.50 − 8.75 = €15.75
Gross Margin = 15.75 ÷ 35 = 45.0%
This comparison leaves out FBA inbound freight — the cost of shipping your inventory to Amazon's warehouse — so even this corrected 45% margin is slightly optimistic for sellers who pay meaningful inbound shipping. The qualitative takeaway holds: FBA carries higher fees than selling on your own Shopify store, but the gap is closer to 10 points than 20.
The product lost roughly 10 gross-margin points just by moving platforms. If ad cost per unit stays near €5, net profit becomes €10.75 per unit instead of €14.18. That is the difference between a product you can scale confidently and one where any ROAS wobble causes pain.
This is why product profitability should always be calculated at the unit level first and the monthly level second. Unit-level math tells you whether the product works. Monthly math tells you whether the volume is large enough to matter.
If the product clears a healthy net margin but volume is low, the next problem is demand generation. If volume is high but net margin is weak, the next problem is pricing, cost control, or channel mix. The same profitability model helps separate those problems cleanly.
The Most Common Mistakes
- Forgetting payment processing fees. On a €35 Shopify sale, the fee is €1.32. Ignoring it overstates gross margin by roughly 3.8 percentage points before you even look at ads.
- Not dividing ad spend by units sold. €300 monthly spend across 60 units is €5 per unit. Treating that as general overhead instead of unit cost can make a mediocre product look excellent.
- Using the supplier quote as full COGS. Import duty, freight-in, packaging inserts, and prep charges can add 15% to 25% to effective landed cost on many sourced products.
- Comparing products only on per-unit profit. A SKU earning €14 at 60 monthly sales creates €840+ in monthly profit, which can outperform a SKU earning €22 at just 20 monthly sales.
Industry Benchmarks
| Net Margin | What's Typical | What's Concerning | |-----------|----------------|-------------------| | Below 10% | Barely viable for paid acquisition | One return spike or ad-cost increase can wipe profit | | 10% to 20% | Workable in many stores | Scaling room is limited | | 20% to 35% | Solid for most ecommerce categories | Usually healthy enough to optimize rather than cut | | 35%+ | Excellent unit economics | Strong ability to scale and discount selectively |
These bands get unreliable when returns, inbound freight, or marketplace-specific fees vary sharply by category, because headline net margin can move more than the table suggests.
Calculate It For Your Numbers
Use the Product Profit Calculator
Related Guides
How To Price an Ecommerce Product shows how to set the selling price before this profitability model is even tested.
How To Calculate Break-Even ROAS translates product margin into the minimum ad efficiency you need to stay out of trouble.
Related Terms
The three reference pages that pair with this guide are gross margin, ROAS, and CAC.