What is MER?
Nicklas Segatz Mortensen · Growth Hacker · Fractional CMO · Meta Ads Nerd · 8 July 2026 · 6 min.
Definition
MER (Marketing Efficiency Ratio) is your total revenue divided by your total marketing spend across every channel. It ignores the platforms' own attribution and shows how efficiently the whole marketing machine is working.
Also called: Marketing Efficiency Ratio, Blended ROAS, aMER, bMER
Sådan virker det
Hver platform tilskriver sig de samme salg — lagt sammen bliver det 130 % af den faktiske omsætning. MER ignorerer attribution og måler den samlede omsætning mod det samlede forbrug.
01Why MER exists
Because Meta, Google, TikTok and Pinterest each credit themselves with sales, the same order gets counted several times. Add up the platforms' reported revenue and you can hit 130% of your actual revenue. MER solves this by ignoring attribution entirely and looking at the total.
MER = total revenue / total marketing spend. No crediting, no double-counting — just what came in and what it cost to bring it in.
02aMER and bMER
Some distinguish between aMER (only paid channels in the denominator) and bMER (all marketing spend, including agency and tooling costs). The point is the same: measure efficiency at a level where the numbers can't be inflated by any single platform.
MER is especially strong at catching incrementality from the top down: if you turn budget up and MER holds or rises, the growth is healthy. If MER falls, you're buying revenue you'd have gotten anyway.
03MER as a steering metric
We use MER as the top-line gauge and POAS/contribution margin to steer within it. MER tells you whether the machine as a whole is efficient; POAS tells you where inside the machine the budget should go.
04A worked example — and the scaling test
Picture a quarter: Meta reports ROAS 5, Google ROAS 8, email ROAS 20. Impressive on their own — but add up the attributed revenue and it exceeds your actual revenue, because the channels credit themselves for the same orders. MER cuts through the noise: total revenue of €160k divided by total spend of €40k gives a MER of 4.0. No platform can inflate that number.
MER's real strength is as a scaling test. Turn the budget up 20% and watch: if MER holds or rises, the extra revenue was incremental — genuinely new growth. If MER falls while platform ROAS still looks great, you bought sales you'd have gotten anyway. It's the cheapest incrementality test there is, and it takes nothing more than reading the total.
One important nuance: MER has to be read alongside CLTV. A brand with strong retention can deliberately run a lower MER in a growth phase, because the customer value is realized over the coming months. MER tells you the efficiency today; CLTV tells you whether a lower MER today is an investment or a leak.
Frequently asked questions
What's the difference between MER and ROAS?+
ROAS is often a platform's own attributed revenue for one channel. MER is your total revenue against your total marketing spend — with no attribution. MER can't be inflated by the platforms and is therefore a more honest measure of efficiency.
What is a good MER?+
It depends on margin and the share of repeat purchases. A brand with strong retention can drive growth at a lower MER, because the customer's value is realized over time. So MER should always be read alongside CLTV and contribution margin.
Related terms
Glossary
What is POAS?
POAS (Profit on Ad Spend) is your gross profit divided by ad spend. Where ROAS measures revenue per ad euro, POAS measures what you actually keep — after cost of goods, shipping and fees.
Read the entry →Glossary
What is ROAS?
ROAS (Return on Ad Spend) is the revenue generated by ads divided by ad spend. A ROAS of 4 means €4 in revenue for every ad euro — but says nothing about what you actually keep.
Read the entry →Glossary
What is incrementality?
Incrementality is the added effect a marketing effort creates: the sales that happened only because the ad ran. Sales you'd have gotten anyway aren't incremental — whatever the platform credits.
Read the entry →Glossary
What is CLTV?
CLTV (Customer Lifetime Value) is the total gross profit an average customer contributes across their entire lifetime as a customer — from first purchase to last.
Read the entry →MER-based steering is at the core of how Profit Forge allocates budget across channels.
See Profit Forge →
Nicklas Segatz Mortensen
Growth Hacker · Fractional CMO · Meta Ads Nerd at Oaksmond
Growth hacker and fractional CMO with 10+ years' experience and hundreds of millions in managed ad spend behind him. Background from larger Danish and international scale-ups, and from the agency world.
Meet the team →