ROAS (return on ad spend)

ROAS is attributed sales divided by media cost: the revenue an attribution model credits to a campaign, within a stated window and on a stated basis (click or view), per unit of spend.

ROAS depends entirely on the attribution rules behind the numerator. The IAB/MRC guidelines define attributable direct sales as "outcomes that can be attributed to a viewable ad based on MRC viewability standards, associated to specific SKUs included within the creative or directly determined by the brand partner," and require networks to "disclose if attribution is based on viewability or extrapolation" (IAB/MRC, January 2024, outcomes table). IAB Europe's V2.1 adds that ROAS "is typically based on a last click or view model," that networks "should provide a split between click-based and view-based ROAS," that the default lookback is 30 days post-click and post-view, and that a sale is gross unless net is stated (IAB Europe, V2.1).

Because ROAS rises with longer windows, view-through credit, halo inclusion and gross rather than net sales, two networks' ROAS figures are comparable only when those four settings are disclosed and equal. That is why the standards treat ROAS as a reporting metric and incrementality as the performance metric.

Example: a sponsored-products campaign spends $50,000 and is credited with $400,000 of same-SKU sales within 14 days of a click: ROAS 8.0. With view-through credit and a 30-day window the credited sales are $620,000: ROAS 12.4. Nothing about the campaign changed.

Related: iROAS, incrementality, closed-loop measurement, take rate.

Source: IAB/MRC, "Retail Media Measurement Guidelines" (January 2024); IAB Europe, "Commerce Media Measurement Standards V2.1" (January 2026).

1. IAB/MRC, January 2024, outcomes table
2. IAB Europe, V2.1