What is the difference between contribution margin and gross margin?
Contribution margin answers a question gross margin cannot: how much does this order actually contribute toward fixed costs and profit? Gross margin stops at cost of goods. Contribution margin keeps going through every cost that scales with volume.
Why does contribution margin matter for advertising?
That distinction matters enormously for advertising decisions. Gross margin might say a product earns 55%, while contribution margin, after $9 shipping, a 3% payment fee, a redeemed discount and a 28% return rate, says it earns 19%. Those two numbers imply completely different bid ceilings.
Should contribution margin be calculated per product?
It should be calculated per SKU, not blended. Blended margin hides the specific case that causes most e-commerce losses: one hero product with thin margin absorbing a disproportionate share of ad spend.
Formula
Contribution Margin = Revenue − COGS − Shipping & Fulfilment − Payment Fees − Discounts Redeemed − Expected Returns
Express it as both a dollar figure per order and a percentage of revenue. The percentage sets your break-even ROAS; the dollar figure sets your maximum acceptable CAC.
Why Contribution Margin matters
It converts advertising from a guessing exercise into arithmetic. Once you know contribution margin as a percentage of revenue, your break-even ROAS is simply 1 ÷ that percentage. Every campaign below it's buying revenue at a loss no matter how healthy the platform dashboard looks.
A worked example
A $90 product with $31 COGS, $8 shipping, $2.70 in payment fees, an average $5.40 in redeemed discounts, and a 12% return rate. Contribution before ad spend is $90 − $31 − $8 − $2.70 − $5.40 = $42.90, then reduced by returns to roughly $37.75, or 42% of revenue. Break-even ROAS is 1 ÷ 0.42 = 2.4x. Any campaign under 2.4x is losing money, even though a 2.0x ROAS looks perfectly respectable in Meta Ads Manager.
Benchmarks
- Healthy DTC contribution margin
- 35–55% of revenue
- Apparel return rate
- 20–40%
- Consumables return rate
- under 5%
Ranges drawn from Digital Squad client accounts and published industry data. Treat them as orientation, not targets. Your category may differ substantially.
Common mistakes
Using a company-wide average
Return rates vary from under 5% in consumables to 40% in apparel. Applying one blended rate across the catalog produces conclusions that are wrong in both directions simultaneously.
Costing discounts at face value
A 15% code that 40% of buyers use costs 6% of revenue, not 15%. Modeling at face value makes truly profitable campaigns look unprofitable and leads to cutting things that work.
Excluding returns entirely
Returns are the most commonly omitted variable cost and often the largest. A 25% return rate in apparel changes the economics of the entire business, not just the returned order.
Forgetting it changes with scale
Shipping costs per unit fall with volume; discount rates often rise as you push into colder audiences. The model needs re-running periodically, not building once.
Where we work on this