Return on Ad Spend ROAS (aka "return on advertising spend")
How much revenue each advertising dollar brought back, as a ratio.
The fork, why two teams get different numbers
PLATFORM ROAS (reported inside Meta/Google) divides platform-ATTRIBUTED
conversion value by spend, inside that platform's own attribution window, it counts view-through and modeled sales and claims credit generously.
BLENDED ROAS / MER divides TOTAL company revenue by TOTAL ad spend and
claims nothing about which ad did what. The two routinely disagree by 2x+:
every platform reports 4x while blended sits at 1.8x, because the platforms
are each counting the same organically-arriving buyers. There is also a
revenue-basis fork, gross order value vs net of returns, discounts, and
tax, that shifts ROAS before attribution is even discussed.
The trap
ROAS is not profit.
- The full trap, worked on a real export
- Every formula variant, spelled out
- The reconciliation anchor, what to tie it to and when to refuse
Reference: IAB (ad measurement · reference) · MRC (attribution guidance · reference)