Gross Margin vs Contribution Margin
Gross margin nets only COGS; contribution margin nets every variable cost. Here's which one belongs in the board deck, which one sets your breakeven ROAS, and how online stores get burned confusing the two.
Gross Margin vs Contribution Margin
Gross margin subtracts only COGS from revenue; contribution margin subtracts every variable cost — COGS, shipping, payment fees, returns, and pick-and-pack.
Gross margin and contribution margin both measure what's left of a sale after variable costs, but they draw the line in different places. Gross margin stops at cost of goods sold (COGS) — the landed cost of the product itself — and is the figure your accountant reports on the P&L. Contribution margin keeps subtracting: payment processing, shipping out, pick-and-pack, return logistics, free-gift inserts, even the referral commission on that order.
For an online store, the gap between the two can be 15-25 percentage points. That gap is the difference between a paid campaign you think is profitable and one that's quietly burning cash.
The short version: gross margin is an accounting metric, contribution margin is an operating metric. Your CFO wants gross margin for the board deck because it ties cleanly to inventory and supplier negotiations. Your performance marketer needs contribution margin because that's the number that decides whether a Meta campaign at 2.4x ROAS makes money or loses it.
Both metrics belong in your stack — using one where the other is needed is where the damage happens. The benchmark below shows the same apparel SKU under both lenses so you can see exactly where the gap opens up.
Same €60 apparel SKU, gross margin vs contribution margin
| Line item | % of revenue | € per unit |
|---|---|---|
| Revenue (AOV) | 100% | €60.00 |
| COGS (landed product cost) | -35% | -€21.00 |
| = Gross margin | 65% | €39.00 |
| Payment processing (Shopify Payments) | -2.4% | -€1.44 |
| Outbound shipping (subsidised) | -6% | -€3.60 |
| Pick, pack & fulfilment | -4% | -€2.40 |
| Returns (25% rate × reverse logistics) | -7% | -€4.20 |
| Free-gift insert / packaging | -1.5% | -€0.90 |
| = Contribution margin | 44.1% | €26.46 |
Gross margin reads 65%. Contribution margin lands at 44.1%. That 21-point delta is the operating reality of running an apparel brand — and it's the floor every paid-acquisition decision should be measured against, not the headline 65%.
When to use which
Use gross margin when the audience is external or the question is about the product itself: investor updates, supplier renegotiations, pricing reviews, SKU rationalisation, year-over-year P&L comparisons. It's the cleanest cross-company metric because it strips out fulfilment choices that vary by operator.
Use contribution margin for every operating decision: breakeven ROAS targets, MER ceilings, free-shipping thresholds, discount approvals, channel allocation, and bundle design. Anything where you're committing variable spend against a single order needs to be measured against the margin that survives all the other variable costs.
The breakeven ROAS trap
Breakeven ROAS = 1 / contribution margin, not 1 / gross margin. The apparel SKU above breaks even at 1 / 0.441 = 2.27x ROAS, not 1 / 0.65 = 1.54x. Brands that anchor on the gross-margin number set ROAS floors 30-40% too low and scale campaigns that look profitable in Ads Manager but lose money at the bank.
Where online operators get burned
The most common mistake is borrowing the finance team's gross-margin number for the marketing dashboard. It feels safe — it's an audited figure — but it ignores that paid traffic disproportionately drives the high-cost behaviours: first-time buyers return more, cold traffic uses discount codes, and prospecting campaigns skew toward lower-AOV orders where flat shipping eats a bigger percentage.
The second mistake is treating contribution margin as a single number for the whole store. A returning customer buying two full-price items in one box has a contribution margin 10-15 points higher than a first-time buyer using WELCOME10 on one item. Segment your contribution margin by customer cohort and channel before you set breakeven targets — the chart below shows how steep the variance gets.
Contribution margin by order type — apparel store, €60 AOV
Frequently asked questions
Gross margin subtracts only cost of goods sold from revenue. Contribution margin subtracts every variable cost — COGS plus payment fees, shipping out, fulfilment labour, returns, and any per-order inserts or commissions. Contribution margin is always lower than gross margin, typically by 15-25 points for online stores.
Contribution margin, always. Breakeven ROAS equals 1 divided by your contribution margin as a decimal. Using gross margin instead sets your floor 30-40% too low and makes losing campaigns look profitable in your ad platform.
Because gross margin only captures the cost of the product. Contribution margin also captures every variable cost that scales with each order: card processing (2-3%), outbound shipping (4-8%), pick-and-pack (3-5%), and returns (which on apparel can cost 5-10% of revenue once reverse logistics and refurbishment are included).
Both, but for different reasons. Gross margin goes on the P&L and is the clean cross-company benchmark investors use. Contribution margin belongs in the operating review because it shows whether the unit economics support the current paid-acquisition strategy. A board deck without contribution margin hides the real picture.
Gross margin typically ignores returns because returned inventory is added back to stock. Contribution margin should include the cost of return shipping, inspection, refurbishment, and any unsellable units. For categories with 25%+ return rates like apparel, this single line can shift contribution margin 5-8 points.
No. Contribution margin nets only variable costs and is calculated per order. Net margin also subtracts fixed costs — rent, salaries, software, brand marketing — and is a whole-business metric. Contribution margin tells you whether one more order is profitable; net margin tells you whether the company is.
Set your free-shipping threshold against contribution margin, not gross margin. If your average contribution margin is €26 per order and shipping costs you €5, free shipping is fine. If a discount code drops contribution margin to €14, that same €5 shipping subsidy now eats a third of the order's profit.
Both. Store-level contribution margin sets your blended breakeven ROAS. SKU-level contribution margin tells you which products to push in paid campaigns and which to bundle or deprioritise. A 70% gross-margin SKU can have a worse contribution margin than a 55% one if it's bulky, fragile, or return-prone.
Monthly at minimum, quarterly for the full segmented breakdown. Shipping rate cards change, payment processor fees creep up, return rates shift seasonally, and discount mix moves with promo cadence. Brands that recalculate once a year are working off margin assumptions that are 6-12 months stale.
No. CAC is subtracted after contribution margin to get contribution profit per customer. Keeping acquisition spend separate is what lets you compare channels: contribution margin is the same regardless of where the order came from, so the channel comparison happens on the CAC line.
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