MER = Total Revenue / Total Marketing Spend
MER is deliberately blunt. It ignores attribution entirely and asks one question: for every dollar the company spent on marketing, how many dollars of revenue did the whole business produce. Because it uses booked revenue from the finance system rather than platform-claimed conversions, it cannot be inflated by overlapping attribution, and it is very hard to argue with in a meeting.
A company books 2,000,000 dollars of revenue in a month and spends 400,000 across every marketing channel, so MER is 5.0. If the platforms collectively claim 3,600,000 dollars of attributed revenue, that claim is visibly impossible against 2,000,000 booked, and MER is the number that exposes it.
MER has become the default board-level efficiency metric precisely because attribution settings cannot game it. Its weakness is the flip side of its strength: it tells the board whether the machine is efficient but not which lever to pull. Most operators report MER upward and channel-level metrics to the team.
Track MER as a trend against a target band rather than as a single number. A stable MER while spend increases is the clearest available evidence that a channel still has headroom.
If MER is the metric under pressure in your next board meeting, the work usually starts with e-commerce SEO.
Work With Me