Media Efficiency Ratio (MER)
Paid MediaAlso: MER · Blended ROAS
Quick definition
Media Efficiency Ratio (MER) is total revenue divided by total media spend across every paid channel combined. Unlike return on ad spend (ROAS), which is measured per platform, MER gives a single blended number for the whole media budget over a given period.
A healthy MER depends entirely on your margin. A low-margin retailer needs a much higher MER to be profitable than a high-margin service business does.
How it varies across Australia
MER varies with margin structure more than with channel mix. Australian ecommerce brands with tighter margins tend to run leaner blended ratios than brands selling higher-margin or considered-purchase products. Comparing MER across businesses tells you less than tracking your own MER over time.
See acquisition benchmarks across Australian industries →What it actually means
Media Efficiency Ratio (MER) answers a simple question badly obscured by platform-level metrics. Add up everything you spent on paid media. Add up everything you made. Divide the second by the first. That's it.
The appeal is that MER can't be gamed by attribution disputes. It doesn't care whether a sale came from Meta, Google, or a retargeting pixel that double-counted itself. It just asks whether the whole system, taken together, made more than it cost.
This is also its limitation. MER treats a campaign spending on brand search (which mostly captures demand that existed anyway) the same as a campaign spending on cold prospecting (which creates new demand). Both dollars go into the same denominator. A business can have a healthy MER while one channel quietly loses money and another is propping up the average.
MER works best as a top-line health check next to a cost per acquisition (CPA) or customer acquisition cost (CAC) view of individual channels. It answers 'is the budget as a whole working' while channel-level metrics answer 'where should the next dollar go'. Used alone, it's a blunt instrument. Used alongside conversion rate and channel-level ROAS, it's a useful sanity check on attribution noise.
MER tells you if the whole engine is running. It won't tell you which cylinder is misfiring.
How to calculate it
MER = Total revenue ÷ Total media spend
Worked example. Spent $20,000 across Meta, Google and TikTok in a month. Generated $80,000 in revenue over the same period. MER = $80,000 ÷ $20,000 = 4. Every dollar of media spend returned four dollars of revenue.
The Australian context
Australian ecommerce brands running across Meta, Google and TikTok simultaneously often lean on MER precisely because iOS tracking gaps make platform-reported ROAS unreliable. A brand can see inflated ROAS on two platforms that are both claiming credit for the same sale, while MER, pulled from actual revenue in Shopify or Xero, keeps the total honest. The tradeoff is that MER says nothing about which of those platforms deserves the next marginal dollar.
Where people get this wrong
Media Efficiency Ratio (MER) vs ROAS
| Media Efficiency Ratio (MER) | ROAS | |
|---|---|---|
| What it measures | Revenue across all paid channels combined | Revenue attributed to one specific channel or campaign |
| Affected by attribution disputes | No, uses total actual revenue | Yes, relies on platform attribution |
| Best for | Total budget health checks | Channel or campaign level decisions |
| Risk | Hides which channel is underperforming | Can be inflated by cross-platform double counting |
Related terms
Common questions
Is MER the same as blended ROAS?
Yes, most marketers use the terms interchangeably. Media Efficiency Ratio (MER) and blended return on ad spend (ROAS) both mean total revenue divided by total media spend across all channels combined, rather than measured per platform.
What's a good MER?
There's no universal target. It depends on your margin, average order value and cost of goods. A business with thin margins needs a higher MER to be profitable than a business selling high-margin services. Track your own trend over time rather than chasing a benchmark.
Why do brands use MER instead of ROAS?
Platform-reported return on ad spend (ROAS) is distorted by attribution overlap and tracking gaps, especially since iOS privacy changes. MER pulls from actual total revenue, so it's harder to inflate and gives a cleaner top-line signal even if it hides channel-level detail.
Can MER tell me which channel to invest more in?
No. MER is a blended total, so it can't isolate individual channel performance. For that you need channel-level cost per acquisition (CPA) or ROAS alongside incrementality testing to see what's genuinely driving growth.
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About New Rebellion
New Rebellion is a marketing intelligence consultancy. We build tools, score Australian businesses on how their marketing actually performs, and publish Debrief every day. This dictionary is part of how we work in the open.
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