eCommerce Growth · 6 min read · 18 September 2026
Contribution margin is the only ROAS that matters
Why scaling brands should move from platform ROAS to margin-aware media decisions.
Platform ROAS flatters the numbers
Ad platforms attribute revenue generously and ignore product costs, shipping, discounts and returns. A campaign at 4x ROAS can lose money on every order.
Work back from margin
Start with contribution margin per order, set a target cost per new customer from that, and let platforms optimise toward the economics you can actually afford.
Separate new and returning customers
Blended figures hide whether you're acquiring or just re-buying existing customers. Report new-customer acquisition cost separately and review it weekly.