In the world of freelance paid media, it is common to rely on performance indicators to assess campaign effectiveness. Two metrics often stand out: ROAS (Return on Ad Spend) and MER (Marketing Efficiency Ratio). Both KPIs are essential, but they answer to different logics.
What is ROAS?
ROAS, or return on ad spend, measures the revenue generated for every euro invested in advertising. It is an excellent indicator for optimizing specific campaigns or channels, such as Google Ads, Meta Ads, or YouTube Ads campaigns.
For example, a ROAS of 4 means that every euro spent on advertising generated 4 euros in revenue.
As a Google Ads freelancer or Meta Ads expert, ROAS is often one of the first indicators you look at to adjust bids or analyze the performance of an ad group.
The limit of ROAS: a view that is too fragmented
Focusing exclusively on ROAS can, however, lead to a siloed view. In my experience as a senior traffic manager, I have observed that this often leads to underestimating the influence of one channel on the others.
A top-of-funnel Facebook Ads campaign, for example, may seem barely profitable on its own, but it feeds the entire funnel and increases conversions on bottom-of-funnel Google Ads campaigns.
MER: a global view of your marketing performance
This is where the MER (Marketing Efficiency Ratio) comes into play. MER is calculated as follows:
MER = Total revenue generated / Total marketing spend (across all channels, over the same period)
Unlike ROAS, MER is not limited to a single campaign or platform. It measures the overall effectiveness of your marketing strategy, taking into account the combined efforts across every lever: Search, Display, Meta Ads, YouTube, Emailing, etc.
Why MER is strategic
MER allows you to:
Understand the real impact of your Paid Advertising campaigns as a whole
Assess marketing efficiency beyond platform silos
Align strategic decisions with broader business objectives
It is a particularly useful indicator when working with e-commerce clients or high-volume brands, often present across several channels. As a PPC Expert, using MER reinforces the relevance of your strategic recommendations.
ROAS + MER: a powerful duo for PPC experts
The ROAS gives the details, while the MER gives the big picture.
Used together, these two indicators provide a precise and comprehensive understanding of performance. As a paid media expert, I use both metrics to steer both micro-optimizations and the long-term vision.