Platform ROAS is lying to you — here's the number that matters

Every ad platform grades its own homework. Meta attributes a purchase to itself if someone saw an ad seven days ago; Google claims the same purchase if they clicked a branded search ad on the way to checkout. Add the two "ROAS" numbers together and you'll often exceed the revenue your store actually made.

The fix isn't a smarter attribution model inside the platforms — it's stepping outside them. Marketing Efficiency Ratio (MER) divides total store revenue by total ad spend across every platform. It's blunt, but it can't be gamed, and it's the number your client's finance team will recognize.

In practice you want both layers: platform-reported ROAS to compare campaigns against each other inside a channel, and blended MER to know whether the whole machine is profitable. The mistake is using the first number for the second job.

This is why AdBreeze Brain connects Shopify and WooCommerce next to the ad platforms. When the dashboard shows spend against real revenue — by day, by country, by product — conversations with clients stop being about whose attribution to believe and start being about where to scale.