MER (Marketing Efficiency Ratio)
Definition
Total revenue divided by total marketing spend across all channels. It is a blended, platform-independent view of whether marketing is paying off.
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Formula
MER = Total Revenue ÷ Total Marketing SpendEach ad platform reports its own ROAS and they often overlap, claiming the same sale. MER sidesteps that by comparing all revenue to all marketing spend, straight from your books.
It is a simple, honest check on whether marketing as a whole is pulling its weight. Watch for: MER falling while platform ROAS looks steady, which usually means the platforms are over-crediting themselves.
Example
$400,000 in monthly revenue and $80,000 total marketing spend gives an MER of 5.0.