Free MER Calculator: Marketing Efficiency Ratio for Ecommerce
MER, or marketing efficiency ratio, compares total revenue with total marketing spend across the business. It gives you a blended view when platform-reported ROAS is fragmented or attribution rules differ by channel.
MER is a blended planning metric. Pair it with channel-level ROAS, cohort retention and profit reconciliation before changing budget.
How this free tool works
Calculate blended MER, marketing spend as a share of revenue, contribution profit and break-even MER across every channel. Free and private. The result is designed to be transparent: you can see the inputs, the formula and the assumptions instead of receiving a black-box score.
MER = total revenue ÷ total marketing spend. Marketing spend as a share of revenue = marketing spend ÷ revenue × 100. Break-even MER = 1 ÷ contribution margin.
Best for
- DTC founders reviewing the whole marketing portfolio
- Operators who want a blended metric alongside channel ROAS
- Teams setting a spend ceiling from contribution margin
Frequently asked questions
What is MER in marketing?+
MER is total revenue divided by total marketing spend for the same period. It shows how much revenue the whole marketing program generated per dollar spent.
Is MER the same as blended ROAS?+
They are often used interchangeably when both use total revenue and total advertising or marketing spend. Define the spend scope explicitly because adding agency fees, creators or software changes the result.
What is a good MER?+
There is no universal target. Compare MER with your contribution margin, cash timing, fixed costs and growth stage; a ratio that looks strong can still be unprofitable when margins are thin.
References and methodology
We use primary documentation where available and treat calculators as planning aids, not guarantees. Check the linked source when a platform changes its rules.
- Shopify: Basic ecommerce metrics
High-authority context for revenue, orders and store performance metrics.
- Google Ads: About return on ad spend
Use alongside channel-level ROAS; MER is a blended business view, not a replacement for attribution QA.
Turn this answer into a repeatable growth workflow.
Use the free result as your starting point, then move the next campaign, creative or growth decision into GrowthGPT when the work becomes repetitive.