Marginal Return on Ad Spend
Definition
Marginal ROAS describes, in revenue-based evaluation, additional revenue per additional advertising spend.
In revenue-based evaluation, marginal ROAS is the ratio of additionally generated, attributable revenue to additional advertising spend. Platforms may instead use a broader conversion value that is not necessarily revenue.
Simply explained
How to check what an additional euro of advertising brings instead of looking at the previous total return.
Why it matters in practice
Helps to manage marketing decisions measurably, comparably, and economically.
Example from business
The last €1,000 spent generates an estimated €1,400 additional revenue according to the model.
Limits and pitfalls
- Confusing marginal with average ROAS and deriving causality from platform attribution.
Origin & history
The concept combines marginal analysis with marketing mix and experimental measurement.
Use in mid-sized companies
- Possible application: A marketing team estimates additional revenue from a budget change. It documents model assumptions and uncertainty and evaluates an increase against revenue and cost requirements.
Frequently asked questions
What does Marginal Return on Ad Spend mean?
In revenue-based evaluation, marginal ROAS is the ratio of additionally generated, attributable revenue to additional advertising spend. Platforms may instead use a broader conversion value that is not necessarily revenue.
Which mistakes should be avoided?
Confusing marginal with average ROAS and deriving causality from platform attribution.
Sources
- research.google
- Ergänzender Primärbeleg · Ergänzender Primärbeleg
- Ergänzender Primärbeleg · Ergänzender Primärbeleg
Source checked on 10.10.2026. Editorial use cases are hypothetical; no evidence of real customer results. Supplementary references checked on 12.10.2026.
Editorially reviewed on: