MER calculator

Marketing efficiency ratio — total revenue over everything marketing costs you.

Runs entirely in your browser — nothing is uploaded, nothing is stored. Updated 2026-09-05.

MER is total revenue divided by total marketing spend. $214,000 of revenue against $52,000 of marketing gives a marketing efficiency ratio of 4.12.

It is deliberately the crudest metric in the stack, and that is the point: it never asks which channel deserves credit, so no amount of attribution disagreement can move it. Where MER differs from blended ROAS is scope — blended ROAS divides by media spend, while MER divides by everything you spend on marketing, agency fees, tooling and salaries included. Itemise those lines below and the calculator returns both, so you can see the gap.

MER against blended ROAS against platform ROAS

Three metrics, same arithmetic, three different scopes — and most arguments about them are really arguments about scope:

• Platform ROAS — that platform's attributed revenue ÷ that platform's spend. Overlaps with every other platform.
• Blended ROAS — all revenue ÷ all media spend. Cannot double-count, tells you nothing about which channel worked.
• MER — all revenue ÷ all marketing cost, media and everything else. The closest of the three to a P&L number.

MER is the number to steer total marketing investment by. It is useless for deciding where the next thousand dollars goes.

The organic problem

MER divides all revenue by marketing spend, which means revenue that would have arrived anyway sits in the numerator. A business with a strong organic base shows a flattering MER that has little to do with its advertising.

This is not fixable inside the metric, and pretending otherwise is where MER gets misused. Track it as a trend rather than a level: MER falling while spend rises is the signal worth acting on, whatever the absolute number is.

What a MER trend actually tells you

Rising MER at flat spend means the same marketing is producing more revenue. Falling MER at rising spend is the classic saturation signature — you are buying further down the demand curve, and the marginal dollar is worth less than the average one.

That second reading is the one MER is genuinely good at, and it shows up in MER weeks before it shows up in any platform-reported ROAS, because platform figures re-attribute as they scale.

Computing this from your own accounts

Every calculator on this page takes numbers you typed. The version that keeps working is the one that reads them from the accounts themselves — which is what TableBI is: connect Google Ads, Meta Ads, GA4 or Search Console once, and roas() becomes a macro you can query from your terminal.

# connect once, then the metric is a standing query
tablebi connect google_ads
tablebi connect meta_ads   # beta: your own or test ad accounts

tablebi ask "WITH w AS (SELECT MAX(date) AS anchor FROM metrics)
   SELECT platform, roas(SUM(revenue), SUM(cost)) AS roas
   FROM metrics, w WHERE date > w.anchor - 30
   GROUP BY platform ORDER BY roas DESC"

# pin the answer to a URL that refreshes itself
tablebi pin --title "MER calculator by channel"
→ https://you.tablebi.com/d/dsh_…

The pinned answer is a live URL that refreshes on its own — here is one running now. No hosted model does the reasoning; your own Claude Code or Codex drives the CLI, which is why there is no inference bill attached to it.

Questions people ask about mer calculators

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