What does MER stand for in marketing?
MER stands for Marketing Efficiency Ratio. It measures how much total revenue a business generates for every pound or dollar spent on marketing, across every channel combined. Unlike ROAS, which relies on each ad platform’s own attribution, MER uses actual revenue from your order system or finance team. That makes it the one efficiency number that can’t be inflated by double counting.
MER is sometimes called blended ROAS. The idea is the same: judge the whole marketing engine, not one campaign, one channel or one platform’s opinion of what it drove.
How to calculate MER
The formula is simple:
MER = Total revenue ÷ Total marketing spend
Use the same period for both figures, usually a month. Total marketing spend should include every paid channel, plus agency fees and tooling if you count them in your budget.
Example: A retailer makes $400,000 in a month and spends $95,000 across Google, Meta, affiliates and agency fees.
$400,000 ÷ $95,000 = 4.2 MER
Every dollar of marketing returned $4.20 of revenue.
MER vs ROAS: what’s the difference?
ROAS (Return on Ad Spend) is calculated per platform using that platform’s attributed revenue. Google and Meta will often both claim the same sale, so adding their ROAS figures together overstates reality. MER sidesteps the problem by using revenue that actually landed.
The trade-off is that MER can’t tell you which channel worked. It’s a governor for the total budget, not a steering wheel for individual campaigns. Use MER to decide how much to spend, and platform ROAS only to compare campaigns inside the same platform.
What is a good MER?
There’s no universal benchmark. A good MER covers your gross margin, fulfilment costs and a profit target. A business with 60% margins can be healthy at 3.0; a business with 25% margins may need 6.0 or more. Track your own MER monthly and watch the trend, not the absolute number. At Corkboard Concepts, rather than just pegging campaigns to fixed numbers like industry standards, we aim to push for positive trendlines in optimization, creating more value over time for companies rather than attempting to just stay above the average.
Is MER the same as blended ROAS?
Yes. Both divide total revenue by total marketing spend. “MER” is the more precise term because it makes clear that no platform attribution is involved.
How often should I calculate MER?
Monthly at minimum, weekly if you’re actively scaling spend. A falling MER while platform ROAS holds steady is a classic sign that platforms are over-claiming.