GLOSSARY
MER (Marketing Efficiency Ratio)
What is MER?
DefinitionMER, the marketing efficiency ratio (also called media efficiency ratio), measures blended efficiency across every channel at once: total revenue divided by total marketing spend. Unlike platform ROAS, it can’t be inflated by multiple platforms each claiming the same conversion.
Formula
MER = Total revenue ÷ Total ad spendFor a telehealth brand where a patient sees Meta and Google ads and an email before subscribing, platform-reported ROAS over-counts revenue by 30–100%; MER is what the bank account actually shows. Your break-even MER is 1 ÷ contribution margin: a brand at 40% contribution margin needs MER above 2.5 before ads add any profit, so a 4.0 MER ($200,000 of revenue on $50,000 of total spend) is healthy there but only break-even for a 25%-margin supplement line. Run your own with the MER calculator.
Related terms
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