What is media efficiency ratio (MER)?
The math is simple. If a business made $2 million in revenue and spent $400,000 on marketing in a month, its MER is 5.0. That doesn't mean marketing caused all $2 million, only that revenue was five times spend.
MER became popular as tracking got less reliable. Because it uses the business's own revenue and spend totals, it isn't affected by missing conversions, ad blockers, or attribution models.
How do you calculate MER?
MER = total revenue / total marketing spend, both measured over the same period.
| Decision | Common choice | Why it matters |
|---|---|---|
| Revenue | All revenue, or new-customer revenue only | New-customer MER isolates acquisition efficiency |
| Spend | Paid media only, or all marketing costs | Including more costs gives a more conservative ratio |
| Period | Weekly or monthly | Longer periods smooth out timing differences |
Whichever definitions a team chooses, they need to stay the same over time, or the ratio stops being comparable.
What is an example of MER?
Platform ROAS vs. the business view
A brand's ad platforms each report a strong ROAS, and together they claim more revenue than the business actually made, because several platforms count the same sale.
MER uses actual revenue and total spend, so it shows the real blended efficiency. When MER falls while platform ROAS holds steady, the team knows the platform numbers are overstating results.
MER vs. ROAS
| ROAS | MER | |
|---|---|---|
| Formula | Attributed revenue / spend for a channel or campaign | Total revenue / total marketing spend |
| Level | Channel, campaign, or ad | Whole business or brand |
| Depends on tracking | Yes | No |
| Shows what drove results | Partly | No |
| Best used for | Optimizing within channels | Checking overall efficiency |
Why does MER matter?
MER is a simple reality check. It tells leadership whether marketing as a whole is getting more or less efficient, independent of how each platform reports its own results.
- Resistant to signal loss. It uses revenue the business recorded, not conversions platforms tracked.
- No double counting. Each sale is counted once, even when several platforms claim credit for it.
- A shared number with finance. It uses the same revenue figure finance reports.
- Limited on its own. It doesn't say which channel to change, so it needs channel-level modeling alongside.
How does Alli do this?
A ratio like MER is only useful when revenue and spend are defined the same way every time. Alli Semantic Layer defines every KPI once, so finance and marketing see the same numbers in every dashboard and model.
To go beyond the blended view, Alli Scenario Planner models media response by channel alongside brand equity signals, so teams can see which channels are driving efficiency and test budget shifts before spend is committed.
Explore Alli Scenario PlannerMedia efficiency ratio FAQ
What does MER stand for in marketing?
MER usually stands for media efficiency ratio or marketing efficiency ratio. Both refer to total revenue divided by total marketing spend.
What is a good MER?
It depends on margins, business model, and growth goals. A good MER is one that covers costs and leaves the profit the business needs, and the trend over time is often more useful than any single number.
Is MER the same as blended ROAS?
Yes, in most usage. Blended ROAS is another name for the same top-down ratio, as opposed to channel ROAS, which uses revenue attributed to one channel or campaign.
Should MER replace ROAS?
No. MER can tell you efficiency fell, but not which channel to fix. Most teams track MER at the business level and use ROAS, mix modeling, and tests to manage channels.
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