ROAS is lying to you. Why we optimize for MER.
Your Meta dashboard shows 4.0 ROAS, your bank account disagrees. Why platform ROAS misleads — and what we steer by instead.
When your Meta ROAS reads 4.0, TikTok 2.5 — and real revenue still doesn't add up, it's rarely you. It's ROAS itself.
Why ROAS lies
- Double-counting: Meta and TikTok both claim the same conversion. Add the platform revenues up and you "sold" more than your till shows.
- Inflated since iOS: modelled conversions and generous attribution windows flatter the numbers inside the ad account.
- Blind to organic: platform ROAS ignores who would have bought anyway.
What MER is
MER = Marketing Efficiency Ratio = total revenue ÷ total ad spend. One number, no black box, unspoofable by attribution. It answers the only question that matters: for every euro of advertising, how much total revenue comes in?
Platform ROAS is the channel's opinion of itself. MER is the truth of your till.
How we use it
- MER as the north star for overall profitability — with a target MER that matches your margins.
- Platform ROAS only relatively: useful to compare campaigns against each other, not as absolute truth.
- Incrementality tests to measure what advertising truly adds — not just what it claims.
The point
Optimise for the number your bank sees, not the one your ad account wishes for. Brands that steer by MER make better budget calls — and never get surprised by a pretty dashboard and an empty account.
Want this on your account?
30 minutes, we'll show you exactly how we'd run it for your brand. No pitch deck.
Book a Growth Audit →