Key takeaways
- COGS is the direct product cost of units sold—not marketing, rent, or outbound shipping (for most DTC models).
- Use landed cost per SKU (invoice + inbound freight + duty + direct packaging) for planning; use inventory roll-forward for accounting periods.
- Gross margin from COGS is necessary but not sufficient: shipping, fees, and returns often erase a “good” product margin.
- Hero SKUs with low COGS can subsidize accessories only if you model mix intentionally, not by accident in a blended average.
- Rehearse COGS and margin trade-offs in the Ecommerce Simulator before you commit to a promo or supplier MOQ.
Definition
COGS (cost of goods sold) — the direct cost of the products you sold in a period: supplier invoices, manufacturing, inbound freight, duty, and packaging tied to units that left inventory. Revenue minus COGS is gross profit. COGS answers “what did the merchandise cost?” before shipping to customers, payment fees, ads, and overhead.
COGS formula
Period COGS = Beginning inventory + Purchases (and production) − Ending inventory
For day-to-day ecommerce planning, operators usually work in landed cost per unit:
Landed COGS per unit ≈ Product invoice + Inbound freight + Duty + Direct packaging
Gross margin % = (Revenue − COGS) ÷ Revenue
Example: you sell a SKU for $72 and landed COGS is $26.40 → gross profit $45.60 → gross margin 63.3%. That is merchandise margin only—outbound shipping, payment fees, and returns still sit between gross profit and contribution margin.
What to include vs exclude
| Usually in COGS | Usually outside COGS |
|---|---|
| Supplier product cost | Paid media and affiliates |
| Inbound freight and duty | Outbound shipping to customers |
| Direct manufacturing labor (if you produce) | Payment processing fees |
| Packaging that ships with the unit | Warehouse rent and salaries |
| Co-packer fees tied to units produced | Returns processing (often in contribution) |
The split matters because a store can show 60% gross margin and still lose money per order after $9 of net shipping and 3% payment fees. COGS is the foundation of gross margin; unit economics needs the full variable stack.
What the number hides / common mistakes
- Stale supplier quotes — FX, freight, and MOQ discounts move COGS; using last year’s $18 cost on a $22 invoice makes every dashboard lie.
- Blended average COGS — a hero SKU at 70% gross margin hides an accessory line at 35%. Promo bundles can pull COGS up while revenue looks flat.
- Forgetting inbound freight — “$12 product cost” that is really $15 landed is a 25% planning error on contribution.
- Confusing gross margin with contribution — celebrating COGS wins while free shipping eats the gain. Read gross margin next to contribution, not instead of it.
- Inventory write-downs ignored — dead stock that never sold does not hit COGS until you write it off or sell at clearance; cash left earlier.
- Mixing accounting methods — FIFO vs weighted average changes period COGS when costs are rising; finance and growth must use the same method in meetings.
Worked ecommerce example
A skincare DTC brand sells two SKUs in one month. 2,400 orders, blended AOV $68. Revenue $163,200. Below is merchandise COGS only (landed, per unit sold).
| SKU | Units sold | Revenue | Landed COGS / unit | COGS total | Gross margin % |
|---|---|---|---|---|---|
| Hero serum (30ml) | 1,800 | $126,000 | $19.20 | $34,560 | 72.6% |
| Travel refill | 600 | $37,200 | $14.80 | $8,880 | 76.1% |
| Blended | 2,400 | $163,200 | — | $43,440 | 73.4% |
Blended gross profit = $119,760. Sounds strong—until variable fulfillment: outbound shipping net of customer-paid ($6.20/order average) = $14,880; payment fees ~2.9% = $4,733; expected returns 7% of revenue with partial recovery = ~$6,100. Contribution before ads ≈ $94,047, or ~57.6% of revenue—not 73.4%. If they spent $52,000 on acquisition for 2,100 new customers, CAC ≈ $24.80 while contribution per order ≈ $39.19—payback looks fine on paper only if repeat purchase shows up.
A 4% COGS reduction on the hero serum (negotiated freight + packaging redesign) saves $0.77 per unit × 1,800 = $1,386/month in gross profit—more durable than a 10% off promo that also trains customers to wait for discounts. That is the kind of lever you model in product profitability analysis.
For many branded DTC categories, landed COGS often lands near 25–45% of retail price before outbound shipping—wide band; replace with your supplier invoices and freight bills.
Source: Growthegy operator practice; see product profitability and margin guides (2026)
How to read COGS in the Ecommerce Simulator
In the Ecommerce Simulator, product cost (COGS) is an input that flows into gross margin and then contribution. Practical rhythm:
- Set AOV and COGS % (or dollar COGS) to match your hero SKU landed cost, not list price fantasy.
- Add shipping, fees, and refund assumptions—the simulator separates merchandise margin from what is left after variable fulfillment.
- Run margin-first: lower COGS 3 points and read contribution per order and payback before you touch ad budget.
- Compare a “supplier MOQ discount” scenario (lower COGS, higher cash tied in inventory) against status quo—COGS wins on paper can lose on cash if inventory turns slow.
COGS is not a slider you optimize in isolation. Pair simulator output with supplier and inventory management so a cheaper unit does not become twelve weeks of the wrong SKU in the warehouse.
Related terms
- Gross margin — revenue minus COGS.
- Gross profit — dollar gross margin.
- Contribution margin — after shipping, fees, and returns.
- AOV — revenue per order; COGS scales with mix.
- Inventory turnover — how fast COGS cash cycles.
Back to the ecommerce glossary. COGS is the merchandise truth layer—keep landed cost current, model SKU mix, and never confuse a strong gross margin slide with a store that pays back CAC.