MER and blended ROAS calculator
MER, the marketing efficiency ratio, divides all revenue by all marketing cost. Blended ROAS divides it by ad spend alone. Both use the revenue your store or billing system records, so neither depends on how any ad platform attributes conversions.
Reviewed Oct 3, 2026
- MER
3.33x3.33x - Blended ROAS
4.00x4.00x - Marketing cost share of revenue
30.0%30.0% - Break-even MER
2.22x2.22x - Contribution after marketing
$18,000$18,000
01
What MER means in marketing
MER, the marketing efficiency ratio, is total revenue divided by total marketing cost over the same period. A MER of 3.33x means the business brought in $3.33 of revenue for each dollar spent on marketing, whichever channel was credited.
Definitions vary between teams. This calculator counts ad spend plus the other costs of marketing, such as agency fees, tools and creator payments, in MER, and ad spend alone in blended ROAS. When a team has no costs beyond ad spend, the two figures are equal.
02
Why blended figures complement platform ROAS
Meta and Google each attribute conversions under their own rules, and the same order can be credited by both. Adding their ROAS figures overstates what paid media produced. MER and blended ROAS start from the revenue the store actually recorded.
Platform ROAS remains the tool for choosing between campaigns inside one platform. MER answers a different question: whether the total marketing budget is paying for itself.
03
Find a good MER for your margin
Break-even MER is 1 divided by contribution margin, the same arithmetic as break-even ROAS. Below it, marketing costs more than the contribution its revenue leaves. A 45% margin breaks even at 2.22x.
Revenue from returning customers raises MER without any new acquisition. Some teams therefore also compute it on new-customer revenue only, which shows whether marketing is still buying growth.
- Use one period and one currency for revenue and costs
- Use revenue net of refunds when refunds are material
- Read the trend over weeks rather than a single day
04
Follow MER without a spreadsheet
Adrails reads Shopify or Stripe revenue next to the spend of the ad accounts you connect, so the blended figure can be followed every day instead of being rebuilt from exports. The calculator above stays free and runs in your browser.
Three ratios
MER, blended ROAS and platform ROAS
The formulas look alike. The revenue they use is what separates them.
| Metric | Formula | Revenue source | Answers |
|---|---|---|---|
| Platform ROAS | Attributed revenue ÷ that platform's spend | The ad platform's attribution | Which campaigns the platform credits |
| Blended ROAS | Total revenue ÷ total ad spend | Store or billing system | Whether paid media as a whole pays back |
| MER | Total revenue ÷ total marketing cost | Store or billing system | What the business gets for all of its marketing |
Worked example
MER for a month of $120,000 in revenue
| Step | Calculation | Result |
|---|---|---|
| Total ad spend | $18,000 + $9,000 + $3,000 | $30,000 |
| Total marketing cost | $30,000 + $6,000 | $36,000 |
| Blended ROAS | $120,000 ÷ $30,000 | 4.00x |
| MER | $120,000 ÷ $36,000 | 3.33x |
| Break-even MER | 1 ÷ 0.45 | 2.22x |
| Contribution after marketing | $120,000 × 45% − $36,000 | $18,000 |
The calculator's default inputs: $120,000 of revenue, $18,000 on Meta, $9,000 on Google, $3,000 on other ads, $6,000 of agency and tool fees and a 45% contribution margin.
FAQ
Common questions
What is MER in marketing?
MER, the marketing efficiency ratio, is total revenue divided by total marketing cost for the same period. It measures the whole marketing budget against the revenue the business recorded.
Is MER the same as blended ROAS?
Often they are used as synonyms. Here, blended ROAS divides revenue by ad spend only, while MER also counts other marketing costs such as agency fees and tools. With no costs beyond ad spend, they are equal.
What is a good MER?
One above your break-even MER, which is 1 divided by your contribution margin. A business keeping 45% of revenue after variable costs breaks even at 2.22x; any profit target sits above that.
Does the calculator connect to my store or ad accounts?
No. It runs in your browser with the figures you enter and does not upload them.