Why your ROAS looks different on every platform
Google Ads says your return on ad spend is one figure, Meta says another, GA4 a third. Same campaigns, same spend, three answers. It is not a maths error; each is dividing a differently-counted revenue by the same cost.
Why the numerator differs
ROAS is revenue divided by spend. The spend is the same, but the attributed revenue is not. Each platform credits itself for conversions on its own rules, so Google's revenue, Meta's revenue (often inflated by view-through) and GA4's last-click revenue are all different numbers over the same sales.
What pulls them apart
- Attribution model: last-click vs data-driven vs view-through.
- Attribution window: a 7-day click window captures more than a 1-day one. See attribution windows.
- Double counting across platforms, as with Meta vs Google Ads conversions.
Which number to act on
Use each platform's ROAS to judge that platform against itself over time (is it improving?), not to compare platforms head to head. For a true blended picture, calculate ROAS from total revenue (your store or GA4) against total spend, often called MER. One honest blended number beats three self-serving ones. Clean, consistent conversion tracking is what makes any of it trustworthy.
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