The difference
- ROAS focuses on revenue per ad dollar: revenue / ad spend.
- ROI focuses on profit relative to total cost: (revenue - cost) / cost.
- A high ROAS can still have a negative ROI if margins or costs are poor.
When to use ROAS
- Channel/campaign optimization when you have stable margins and costs.
- Topline testing, creative iteration, and early funnel comparisons.
- When profit data is hard to attribute cleanly at campaign level.
When to use ROI
- Budget allocation across initiatives (ads vs content vs partnerships).
- When you can include incremental costs reliably (fees, labor, tools).
- When profitability, not just revenue, is the decision metric.
Attribution pitfalls
- Use the same attribution model and window for comparisons.
- Avoid mixing platform-reported conversions with last-click analytics without a clear rule.
- For mature accounts, validate with incrementality tests when possible.