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Written by MetricKit EditorialReviewed by MetricKit Editorial ReviewUpdated 2026-05-09
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MER Calculator

Calculate MER (Marketing Efficiency Ratio / blended ROAS) and estimate break-even and target MER from margin assumptions.

This MER calculator uses total revenue divided by total marketing spend over the same period. It's a useful top-down health metric that reduces channel attribution noise.

To make MER decision-useful, translate it into profit using contribution margin and compute break-even and target MER thresholds.

Prefer an explanation- Read the guide.
Related definitions:merblended roascontribution margingross marginroasincrementality
MER (blended ROAS): how to use it without fooling yourselfPaid ads measurement hub: ROAS, MER, marginal ROAS, and incrementalityAttribution vs incrementality: what to trust, when, and how to testUTM + GA4 attribution: practical tracking for paid ads (without lying to yourself)
 
$
 
$
Used to estimate max spend at your revenue level.
Used to estimate profit and break-even/target MER.
%
Percent of gross profit to keep as profit (target MER increases as buffer increases).
%
Used to estimate required revenue for a profit target.
$
Tip: you can type commas (e.g., 10,000).

Example

Using the default inputs, the result is:
5x
Total revenue (same period)
$500,000
Total marketing spend (same period)
$100,000
Target MER (optional)
3
Contribution margin (optional)
40%
Profit buffer (optional)
20%
Target profit (optional)
$0

How to calculate

  1. Enter total revenue and total marketing spend for the same window.
  2. Enter contribution margin to estimate gross profit after variable costs.
  3. Optionally set a profit buffer to compute a target MER (more conservative than break-even).

Formula

MER = revenue / marketing spend; Profit ~ revenuexmargin - spend; Break-even MER = 1 / margin
  • Uses contribution margin as a simplified proxy for gross profit after variable costs.
  • Revenue and spend are measured over the same period and on the same attribution basis.
  • MER is top-down; use channel-level metrics for optimization.

Benchmarks

  • Break-even MER is 1 / contribution margin (a floor, not a scaling target).
  • If profit after spend is negative at the blended level, scaling spend typically scales losses unless mix or margin improves.
  • Use MER for top-down health and use channel metrics (ROAS, marginal ROAS) for allocation decisions.

FAQ

Is MER the same as ROAS-
It's a blended version. ROAS is often channel/campaign-level attributed revenue / spend. MER uses total revenue / total marketing spend, which reduces attribution noise but hides what's driving performance.
How do I pick a profit buffer-
Start with 10-30% of gross profit as buffer for uncertainty, overhead, refunds, and measurement error. More volatility and longer payback generally require a larger buffer.

Common mistakes

  • Using MER alone to optimize channel budgets (it hides what's working).
  • Mixing time windows (weekly spend with monthly revenue).
  • Ignoring promos/seasonality and concluding performance changed structurally.

Related calculators

Paid Ads
ROAS Calculator
Calculate Return on Ad Spend (ROAS) and estimate contribution profit after ad spend.
Paid Ads
Break-even ROAS Calculator
Estimate the break-even ROAS based on contribution margin assumptions.
Paid Ads
Target ROAS Calculator
Estimate a target ROAS to cover variable costs plus a desired margin buffer.
Paid Ads
Paid Ads Funnel Calculator
Model CPM -> CTR -> CVR to estimate CPC, CPA, ROAS, and profit per 1,000 impressions (with margin and variable costs).
Paid Ads
ROI Calculator
Calculate Return on Investment (ROI) for a campaign or project.
Paid Ads
Incrementality Lift Calculator
Estimate incremental conversions, incremental ROAS, and incremental profit from a holdout test.

Quick checks

  • Keep attribution model and window consistent when comparing campaigns.
  • Pair efficiency metrics (ROAS/CPA) with profit assumptions (margin, refunds, fees).
  • Validate tracking after site changes (pixels/events can silently break).