ROAS (Return on Ad Spend)
Revenue generated per dollar spent on advertising. ROAS = revenue / spend. A ROAS of 3.0 means $3 revenue for every $1 spent.
Last updated: 2026-05-04
Definition
ROAS is the simplest possible marketing efficiency metric and the easiest to game. Last-click ROAS (Meta and Google's default) systematically over-attributes to the last touch and under-credits brand / consideration channels. Bayesian ROAS adjusts for halo + cross-channel attribution; the two numbers can differ by 30-50% on a typical multi-channel campaign. WatEase shows both side by side in the ROAS Calculator at /tools/roas-calculator so the gap is visible.
How it applies in India
Indian DTC last-click ROAS is typically inflated 25-40% on Meta post-iOS-14.5 — the gap to true Bayesian ROAS is wider than US baselines because Indian users use more web/app cross-device flows.
Related terms
- MER (Marketing Efficiency Ratio)Total revenue divided by total ad spend across all channels. Channel-agnostic; resistant to attribution gaming.
- Bayesian MMMMarketing Mix Modeling implemented with Bayesian inference (typically MCMC sampling), producing posterior distributions over channel contributions instead of point estimates.
- AttributionThe process of assigning credit for a conversion to one or more marketing touches.
- Last-Click Attribution100% credit to the final marketing touch before conversion.
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