Definition
Return on ad spend (ROAS) is the ratio of revenue generated by an ad campaign to the amount spent on it, usually expressed as a multiple. For example, a ROAS of 4x means £4 of revenue for every £1 spent on advertising.
Why ROAS matters
Roas is one of the primary metrics used to judge whether a campaign, ad group, or individual product is spending advertising budget efficiently. It answers a straightforward question: are the ads generating enough sales to justify their cost?
Merchants use ROAS throughout advertising performance dashboards to compare the efficiency of different campaigns, products, or time periods. A higher ROAS indicates better efficiency, while a lower ROAS suggests the campaign may need adjustment, pausing, or replacement with a better-performing alternative.
Roas also helps merchants allocate budget. If one campaign has a ROAS of 5x and another has a ROAS of 2x, the first campaign is delivering more value per pound spent. This metric guides decisions about where to increase spend and where to cut.
Concrete example
Suppose you run an ad campaign that costs £500 over one month. During that month, the platform attributes £2,000 in revenue to that campaign (meaning customers who clicked the ads made purchases totalling £2,000). Your ROAS is calculated as follows:
Roas = £2,000 (revenue) ÷ £500 (spend) = 4x
This means the campaign generated £4 in revenue for every £1 spent.
Important caveat: ROAS measures revenue, not profit
Roas measures attributed revenue against spend, not profit. This distinction matters. A product with a high ROAS may still be unprofitable if its margin is low.
Consider two products:
- Product A: ROAS of 5x, but a margin of only 10 per cent. For every £1 spent on ads, you generate £5 in revenue but keep only £0.50 as profit.
- Product B: ROAS of 2x, but a margin of 60 per cent. For every £1 spent on ads, you generate £2 in revenue but keep £1.20 as profit.
Product B is the better investment, despite its lower ROAS. For this reason, read ROAS alongside your product margin wherever possible. The best advertising decisions combine ROAS with margin data to identify which campaigns and products are truly profitable.
Related terms
Conversion: A customer action resulting from an ad click, such as a purchase or account sign-up. ROAS depends on the number and value of conversions.
Average order value: The mean revenue per transaction. Higher average order values make it easier to achieve a strong ROAS, because each customer generates more revenue.
Incremental sales: Sales that would not have occurred without the ad campaign. Attributed revenue in ROAS calculations attempts to measure incremental sales, though attribution is always an estimate.