Total revenue divided by total marketing spend, across all channels. It ignores which ad gets credit for which sale.
Formula
MER = total revenue ÷ total marketing spend
Example
Meera's website makes ₹4,80,000 in a month from all sources, including ads, WhatsApp, email and people typing her web address. She spends ₹1,20,000 on marketing in total. Her MER is ₹4,80,000 ÷ ₹1,20,000 = 4x.
How you'll hear it
“Meta and Google together claim more sales than we made, so we run the budget on MER and use platform ROAS only to compare campaigns.”
What it helps you decide
Your total marketing budget, using a number that does not depend on any platform's attribution. Platform ROAS is better for choosing between campaigns; MER keeps the total honest.
Where people misread it
People add up ROAS from each platform and believe the sum. Each platform counts sales it touched, so the same order is often claimed twice. MER can also rise for reasons that have nothing to do with ads, such as a festival.
The story
Meera opens both dashboards. Meta claims ₹2,80,000 of sales from her ads. Google claims ₹2,20,000. Together they say her ₹1,00,000 of ad spend made ₹5,00,000: a 5x ROAS.
Then she checks her website's order report.
| Meta-reported sales | ₹2,80,000 |
| Google-reported sales | ₹2,20,000 |
| Claimed by ads | ₹5,00,000 |
|---|
| All website sales, every source | ₹4,80,000 |
| Total marketing spend (ads + freelancer) | ₹1,20,000 |
| MER | 4.0x |
|---|
The ads claim ₹20,000 more than the website sold in total, from every source. Many buyers saw an Instagram ad and later searched on Google. Each platform counted the same sale.
Neither platform is lying. Each uses its own attribution rules. But Meera cannot pay rent with claimed sales. She sets her total budget on MER, which comes from her own records, and uses each platform's ROAS only to compare campaigns inside that platform.
All figures are illustrative.
Compare MER with what platforms claim
The example's numbers are filled in. Replace them with yours.
The platforms claim more sales than you made from every source. They are counting some sales twice.
Don't confuse it with
- ROAS: revenue from ads as one platform counts it, for one campaign or channel.
- Incrementality: whether the ads caused the sales, which MER cannot tell you.
Related terms
Want to use this at work? AI-led PPC Excellence is aFactor's 16-week program for paid ads.
Sources
- Marketing Efficiency Ratio: How To Calculate + Improve MER, Shopify, 2026