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MER vs ROAS
Short answer: use ROAS for campaign-level optimization and MER for blended, business-level efficiency tracking.
Quick answer: if you need to decide where to move spend this week, use ROAS. If you need to report total marketing efficiency to leadership, use MER.
Core Formulas
ROAS = Attributed Revenue / Ad Spend
MER = Total Revenue / Total Marketing Spend
Executive vs Operator Lens
| Question | Use ROAS | Use MER |
|---|---|---|
| Which campaign should get more budget this week? | Yes | No |
| Is total marketing spend improving business efficiency? | Partially | Yes |
| Are strong channels hiding weak channels? | No | Can happen |
Practical Decision Rule
- Set channel-level guardrails with ROAS and break-even thresholds.
- Review blended MER weekly in leadership reporting.
- If MER is falling while ROAS is stable, inspect non-media costs and funnel leakage.