MER vs ROAS
MER (marketing efficiency ratio) is total revenue divided by total ad spend; ROAS is revenue credited to a specific channel divided by that channel's spend. MER cannot be gamed by attribution but is blind to channels; ROAS is channel-level but only as honest as the attribution behind it.
By Joris van Huët, Founder & CEOUpdated 2 min read
Run the numbers for your store: the free blended ROAS (MER) calculator.
What is MER vs ROAS?
MER (marketing efficiency ratio) is total revenue divided by total ad spend; ROAS is revenue credited to a specific channel divided by that channel's spend. MER cannot be gamed by attribution but is blind to channels; ROAS is channel-level but only as honest as the attribution behind it.
Frequently asked questions
When should I use MER instead of platform ROAS?
Use MER (total revenue divided by total ad spend) as your trust anchor whenever platform-reported ROAS is in doubt. It cannot be inflated by attribution modeling because it ignores attribution entirely. Use it to sanity-check, not to allocate.What's the limitation of MER?
MER tells you the blended outcome, not which channel caused it. Two brands with identical MER can have opposite channel realities. Splitting the difference requires incrementality testing or causal attribution on order-level data.