MER calculator
MER is total business revenue divided by total marketing spend, across every channel and regardless of attribution. Eighty thousand of revenue on sixteen thousand of spend is a MER of 5×: marketing costing 20% of revenue.
How to calculate MER
MER became popular precisely because platform-reported ROAS stopped being trustworthy. After privacy changes broke deterministic tracking, the sum of every channel claimed revenue routinely exceeds actual revenue, sometimes by a wide margin. MER sidesteps the problem by refusing to attribute anything: it compares what the business took against what the business spent. The trade-off is that it cannot tell you which channel to cut, so most teams use MER for the health of the whole and platform metrics for relative decisions within it.
Questions
Marketing efficiency ratio. Total revenue divided by total marketing spend, with no attribution modelling at all.
ROAS is per campaign and depends on attribution. MER is company-wide and does not.
It depends on margin and growth stage. Break-even is one divided by gross margin, same as ROAS; established shops often run 4–6×.
Because channels double-count the same sale. That gap is the clearest evidence of attribution inflation you will get.
No. Use it for overall health, and platform metrics or incrementality tests for channel decisions.