What is MER and why does it matter more than ROAS?
Short answer
MER (marketing efficiency ratio) is total revenue divided by total marketing spend across all channels. It matters because it can’t be inflated by platforms claiming the same sale, so it shows whether your marketing is working as a whole.
Each ad platform takes credit generously. If Meta and Google both claim the same order, their ROAS figures add up to more than the revenue you actually received.
Track MER weekly next to platform ROAS, and pair it with new-customer revenue to see whether you are growing or just retargeting existing buyers.
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Answered by ScaleInbox · Reviewed by Shubham Vishwakarma, founder