Hi there,
I was talking to a marketing lead at a large beverage brand this week, and she said something that stuck with me:
"We have a blind spot, and it's very difficult to calculate MER accordingly."
The problem isn’t that she doesn’t know her numbers. It’s that a huge portion of what’s driving the business happens at retail and never makes it back into the data she’s using to measure marketing.
Marketing Efficiency Ratio isn't a new metric. It's the simplest one we have: total revenue divided by total marketing spend. For every dollar you put into media, how much revenue comes out?
What's new is who's asking, and how loudly. 56% of CMOs say their marketing organization doesn't have the budget to deliver on the strategy they're being held to in 2026 [1]. Translation: generate more revenue from every dollar, with fewer dollars, and be ready to prove it worked.
That's the environment MER lives in right now. It's become the go-to metric because it's simple, it's board-friendly, and it cuts through the platform-by-platform noise. Meta says one thing. Google says another. TikTok says a third. MER doesn't care. It just tells you whether the whole machine is working.
MER tells you the number moved. It doesn't tell you why. That's exactly what the marketing leader I mentioned above is running into. Her D2C spend is easy to track, it's all digital, it all closes in the same funnel she already reports on. But the marketing and the ads that drive people into a retail store weeks later? They have no way to attribute that. It still moves her MER. It just does it invisibly, meaning she might’ve already reallocated the budget that caused it, not knowing which campaign drove the sales.
For any brand selling through retail, Amazon, wholesale, or anywhere outside your own checkout, this is the blind spot. The purchase happened. The marketing worked. And the data that would explain which channel, which creative, which audience actually drove it never makes it back to whoever is deciding next quarter's budget. They're left staring at a number that moved and guessing why.
You can watch MER climb or drop for months, hit your target or miss it, and still have no real idea which lever to pull next.
MER used to be a reporting exercise. Now it's an algorithm problem.
Meta, Google, and TikTok aren't optimizing off what you tell them anymore. They're optimizing off what they can verify actually happened. The cleaner the purchase data you feed them, the smarter they get at finding your next buyer. The gaps in that data actively drag down performance.
Most brands are only feeding those platforms one slice of the picture. Globally, ecommerce is still only about 20% of total retail sales [2], which means roughly 80% of what people actually buy happens somewhere the ad platforms can't see. A brand that only sends its DTC sales into that loop is training its algorithms on a fifth of the truth. It looks efficient on paper. It runs inefficiently in practice. And the MER stays stuck for reasons no dashboard will explain.
I don't think MER gets easier to move with tactics alone from here. Tighter creative and smarter bidding still matter, but they're optimizing on top of whatever data the platform already has. The brands that actually move the needle will give their platforms a fuller picture of who's actually buying, and let the algorithm do the rest.
That's a different kind of work than most marketing teams are set up to do. It's not a campaign fix. It's a data problem, sitting one layer below the metric everyone's staring at.
So the question I'd leave you with is: “What is our MER not telling us, and where is that missing piece hiding?”
Talk soon,
Kait
Some of my favorite brands are hiring…
1. Conair - Director of Social, BaBylissPRO
2. SharkNinja - Director, Omnichannel Strategy, Mass Retail
[1] Gartner, 2026 CMO Spend Survey, May 2026.
[2] eMarketer, "Ecommerce to Account for More Than 20% of Worldwide Retail Sales Despite Slowdown."
Kait’s free Sunday newsie on what’s next in performance marketing, AI, and omnichannel growth.
