Best practice
MER vs platform ROAS: why your ads dashboard over-reports
On D2C accounts we audited in 2026, platform-reported revenue ran as high as double what the store actually booked. Here is why that happens, and the one metric that cannot lie to you.
Every ad platform grades its own homework. Meta reports the revenue Meta believes it caused. Google reports the revenue Google believes it caused. Add the two together and you will routinely get more revenue than your store actually collected — because both platforms are claiming the same orders.
This is not a rounding error. On D2C accounts we audited in 2026, platform-reported revenue ran as high as twice what the store booked in a month — month after month, on healthy, well-configured accounts with good pixels. One account's platform claimed more in thirty days than the brand's entire online channel collected.
Why platforms over-report
- Attribution overlap. A buyer who saw a Meta ad and later clicked a Google ad is a conversion in both dashboards. The store only shipped one order.
- View-through credit. Default attribution settings count purchases from people who merely saw an ad within the window — including buyers who were coming anyway.
- Window arithmetic. A 7-day-click window books today's order against last week's ad spend; compare a platform's month to the store's month and the edges never reconcile.
- Organic cannibalisation. Branded search and retargeting sit at the end of journeys the brand had often already won.
The metric that cannot lie
MER — marketing efficiency ratio — is store revenue divided by total ad spend. Spend comes from the platforms, revenue comes from the order system, and nothing is attributed at all. It answers the only question a founder actually asks: for everything we spent on ads this month, what did the business collect?
MER's bluntness is the feature. It cannot double-count. It cannot take credit for a sale the showroom made. And it moves when reality moves: run a genuinely incremental campaign and MER rises; shift budget between channels that claim each other's orders and it stays put — which is exactly the information you need.
How to run on MER
- Build one tracker. One sheet or dashboard: daily spend per platform from the platforms' own reporting, daily revenue and orders from the store. Revenue exists in exactly one column.
- Set your breakeven from margins. Take your real contribution margin and compute the MER at which an order stops losing money. That figure — not a platform benchmark, not an industry average — is your floor.
- Keep platform ROAS as a ranking signal. Inside one platform, a campaign claiming a 10× return is very likely better than one claiming 2×, even if neither absolute is real. Rank with it; never report it as revenue.
- Report the spike next to the baseline. A sale window will post a MER the evergreen account can never match. Publish both numbers side by side, or the spike becomes next quarter's impossible target.
This is how every Markey engagement is measured — it is the first thing we build, before a single campaign changes. See how it played out for Mantara, where the gap between claims and bookings reshaped the whole account, and Deadbear, where one tracker now settles every budget decision.