ROAS looks healthy. So why does the P&L tell a different story?
This is the question we hear most often from ecommerce operators spending £10k+ per month on Google Ads. The dashboard says 4x ROAS. The finance team says margins are shrinking.
Both are telling the truth. That's the problem.
ROAS Is a Lagging Indicator of the Wrong Thing
ROAS measures revenue generated per pound spent. It says nothing about:
- Gross margin on the products that converted
- Return rates that erode reported revenue
- Customer acquisition cost relative to lifetime value
- Cash flow timing between spend and collection
A 4x ROAS on a 20% margin product with a 35% return rate is not a 4x return. It might be break-even. It might be a loss.
The Three Metrics That Actually Matter
1. Contribution Margin Per Ad Pound (POAS)
This is the profit contribution generated per pound of ad spend, after COGS and fulfilment. Unlike ROAS, it tells you whether you're actually making money.
A campaign with 3x ROAS on high-margin products often outperforms one with 5x ROAS on low-margin products. ROAS hides this. POAS reveals it.
2. Return-Adjusted Conversion Value
Your conversion tracking counts the gross sale. But if 30% of those sales come back, you're optimising toward revenue you'll never keep.
We build return-rate assumptions into bidding models. A product with 5% returns gets more budget than one with 40% returns, even if the ROAS looks identical.
3. Payback Period by Cohort
For subscription and repeat-purchase brands, first-order ROAS is almost meaningless. What matters is how long it takes to recover acquisition cost through repeat purchases.
A customer acquired at 1.5x first-order ROAS who subscribes for 12 months is worth more than one acquired at 4x ROAS who never returns.
What This Means for Your Account
If your ROAS looks good but profit feels wrong, the issue is usually structural:
- Bidding optimised for revenue, not margin
- No segmentation by product profitability
- Return rates ignored in performance measurement
- LTV not factored into acquisition targets
These aren't reporting problems. They're commercial problems that require commercial solutions.
What We Look For in Audits
When we review an account, we look at whether the optimisation targets align with actual business outcomes. ROAS is a starting point, not a destination.
If you're spending £10k+ per month and the numbers don't feel right, book a discovery call. We'll show you where the gap is.