How to Calculate True SKU Profitability (And Why Most Brands Get It Wrong)

If you ask a DTC founder which of their products is most profitable, you'll usually get an answer based on gross margin: "This one's at 72%, that one's at 58%." That answer is almost always wrong. Gross margin ignores 60–70% of the costs that actually determine whether a SKU makes you money or quietly drains your bank account.

After running the numbers for dozens of e-commerce brands between $1M and $50M revenue, we see the same pattern: 20% of SKUs generate 80% of true profit, and roughly 15–25% of SKUs are unprofitable when fully loaded. Founders just can't see it because their P&L stops at gross margin.

What "true" SKU profitability actually means

True (or "fully loaded") SKU profitability is the contribution each unit of a specific product makes to the business after every variable and directly attributable cost has been subtracted from its revenue. The formula looks simple:

True SKU profit per unit = Net selling price − COGS − Inbound logistics − Outbound shipping − Payment fees − Returns cost − Discounts/promos − Allocated ad spend − Allocated platform fees − Allocated overhead

Most brands stop after the first three lines. Below is what each of the missing components actually contains.

The 9 cost layers most brands forget

1. Net selling price (not list price)

Take gross revenue, subtract sitewide discounts, coupon codes, bundle discounts allocated to this SKU, loyalty rewards redeemed against it, and chargebacks. The number you sell at on the shelf is rarely the number you actually receive.

2. True landed COGS

Manufacturing cost + inbound freight + duties/tariffs + customs brokerage + insurance + inspection + repacking. For brands importing from Asia this can add 18–35% on top of the supplier invoice. Use weighted-average landed cost per shipment, not the supplier's quoted unit price.

3. 3PL pick & pack + storage

Per-unit pick fee, per-order pack fee, packaging materials and storage cost (allocated by cubic feet × days held). Slow-moving SKUs get crushed here — a $40 product sitting in storage for 9 months can lose 8–12% of its margin to storage alone.

4. Outbound shipping (real, not free)

Even if you offer "free shipping," someone pays. Allocate the actual carrier cost per shipment to the SKUs in that shipment by weight or value. Heavy/bulky low-margin SKUs usually become unprofitable here.

5. Payment processing fees

Shopify Payments / Stripe / PayPal: 2.4–3.5% + $0.30 per transaction, often higher for international cards and BNPL (Klarna, Afterpay can hit 5–6%). Calculate per SKU based on actual order mix.

6. Returns and refunds

Return rate × (return shipping + restocking labor + write-off rate × landed COGS). Apparel SKUs with 30%+ return rates often look profitable until you factor this in — then half of them go red.

7. Allocated marketing spend

Direct attribution where possible (Meta/Google with proper UTM and offline conversion tracking), then allocate the unattributable portion proportionally to revenue or contribution margin. SKUs that ride on hero-product halo effects need a fair share of the spend, not zero.

8. Platform & marketplace fees

Amazon referral fees (8–17%), FBA fees, Etsy 6.5% transaction + 15% offsite ads, Shopify monthly + apps. Allocate per channel to the SKUs sold there.

9. Allocated fixed overhead

Optional but recommended for strategic decisions: software, customer service, finance, founder time. Allocate by units sold or revenue. This shows whether a SKU just "pays its way" at scale.

Worked example: a $49 candle

Selling price: $49 · Discounts/returns adj: −$6 → Net price: $43 Landed COGS: $9 · 3PL pick/pack/storage: $4.20 · Shipping: $7.50 · Payment fees: $1.55 · Returns reserve: $1.10 · Allocated ad spend: $11.80 · Platform/app fees: $0.80 → True profit per unit: $7.05 (16.4% true margin) — vs 81% gross margin.

The "gross margin 81%" candle that the founder thought was a star is actually just barely paying for itself once ads and shipping are real. Now imagine running a 20%-off promo on it.

How to actually do this in practice

• Pull 90 days of order-line data from Shopify/Amazon/your ERP.
• Pull cost data: supplier invoices, 3PL invoices, shipping logs, Stripe/PayPal exports, ad platform spend.
• Build a per-SKU table with all 9 cost layers as columns.
• Calculate true profit per unit and per SKU per period.
• Sort descending. The top 20% is your business. The bottom 20% is what to fix or kill.

What to do with the results

• Unprofitable SKUs: raise price, renegotiate COGS, reduce ad spend, or discontinue.
• Profitable but slow movers: bundle them with hero SKUs to clear inventory and lift order value.
• True hero SKUs: protect them — never discount these, double ad spend.
• Use this view to set discount floors so promos never push a SKU below break-even.

If you want this run on your business, we deliver SKU-level profitability dashboards as part of every fractional CFO engagement. Most clients find $40K–$200K of trapped margin in the first analysis.