What is MER (Marketing Efficiency Ratio)?
Short answer: MER (marketing efficiency ratio) is your total revenue divided by your total marketing spend over a period. Unlike platform ROAS, it doesn’t care which channel claimed the sale — it tells you how efficiently your entire marketing budget turns into revenue.
The MER formula
- MER = total revenue ÷ total marketing spend
- Example: $200,000 revenue ÷ $50,000 total ad spend = MER of 4.0
MER is sometimes called “blended ROAS” because it uses one top-line revenue number over one total-spend number, instead of per-platform reported figures.
Why MER exists: the attribution problem
If Google says it drove $80k and Facebook says it drove $70k, but your store only made $120k, the platforms are double-counting — both took credit for the same buyers. Per-platform ROAS figures rarely add up to reality. MER sidesteps this entirely: it uses your actual total revenue from your store or accounting system, so there’s nothing to double-count.
MER vs ROAS: when to use each
- Use MER to judge overall marketing health and make budget-level decisions — it’s your single source of truth.
- Use ROAS to optimize within a platform — comparing campaigns, ad sets, and creatives where platform data is directionally useful.
For a deeper side-by-side, see ROAS vs MER and blended ROAS explained.
What is a good MER?
There’s no universal number — it depends entirely on your gross margin. A business with 70% margins can thrive at a MER of 2.5, while a 25%-margin business may need a MER of 5 or more just to break even after product costs. The right way to set a target:
- Break-even MER = 1 ÷ gross margin. At 40% margin, break-even MER = 1 ÷ 0.40 = 2.5.
- Set your target MER above break-even to leave room for overhead and profit.
How to use MER day to day
- Track it weekly or monthly, not hourly — MER is a strategic metric, not a bid-level one.
- Watch the trend. A falling MER while spend rises is an early warning that you’re scaling into less efficient audiences.
- Pair it with new-customer MER. Blended MER can be propped up by repeat buyers; tracking MER on first-time customers shows true acquisition efficiency.
Common mistakes
- Comparing MER to ROAS targets directly. They’re measured differently; a “good” ROAS of 4 is not the same bar as a MER of 4.
- Excluding some spend. MER should include all marketing costs you want to hold accountable — agency fees and creative too, if you’re judging total efficiency.
- Using revenue gross of refunds. Use net revenue for an honest ratio.
FAQ
Is MER the same as blended ROAS?
Effectively yes. Both divide total revenue by total spend. “MER” is the more common term among DTC brands; “blended ROAS” describes the same calculation.
Should MER use revenue or profit?
MER traditionally uses revenue. To judge profitability, compare your MER to your break-even MER (1 ÷ gross margin) rather than switching the numerator to profit.
Can MER replace ROAS entirely?
No. MER is best for overall and budget decisions; you still need platform ROAS to optimize individual campaigns and creatives.