Return on ad spend (ROAS)
Short definition
Return on ad spend (ROAS) shows the revenue generated for every unit spent on advertising.
ROAS is calculated by dividing revenue attributed to advertising by ad spend, usually expressed as a ratio. It ignores profit margin, so it is a revenue measure rather than a profitability measure. Miss that distinction and a campaign that grows revenue can still be losing the business money.
Because different product lines carry different margins, the same ROAS can be profitable for one product and loss-making for another. Targets are therefore set at product level rather than managed against a single blanket figure. Costs such as shipping and returns need to be factored in too, or a ROAS target ends up assuming a profitability that is not really there.
In automated campaigns such as Performance Max, a target ROAS is entered as a setting and the algorithm adjusts bids against it, but with weak conversion tracking that target gets optimised against the wrong data.
Why it matters
ROAS is the core measure used to decide where advertising budget should go, by channel or by product. Overlook margin and even a healthy ROAS can hide a campaign that is losing money. Reading it product by product, alongside margin, is what confirms the budget is actually going somewhere profitable.
Illustrative example
When an event equipment hire business set a separate ROAS target for its lower-margin lines, overall revenue stayed level but the budget split shifted in a way that improved profitability.
