MER calculator with break-even
Enter your store revenue, all marketing costs and your contribution margin before marketing. The calculator returns your MER, the MER you need to break even, marketing as a share of revenue and the contribution margin left after marketing. The starting values fit a store with $500,000 in monthly revenue.
Check whether your total marketing pays off
- Marketing spend as % of revenue20.0%
- Contribution margin after marketing$100,000
An MER of 5.00 clears your break-even of 2.50. After marketing, $100,000 remains for fixed costs and profit.
Marketing efficiency ratio formula
Both sides of the formula cover the whole business. Revenue is every sale in your store, no matter which channel gets credit for it. Marketing costs include ad spend on every platform, plus agency fees, tools and creator payments.
| Step | Calculation | Result |
|---|---|---|
| MER | $500,000 ÷ $100,000 | 5.00 |
| Marketing share of revenue | $100,000 ÷ $500,000 | 20% |
| Contribution margin before marketing | $500,000 × 40% | $200,000 |
| Contribution margin after marketing | $200,000 − $100,000 | $100,000 |
An MER of 5 means each marketing dollar goes along with $5 in total revenue. Of every sales dollar, 20 cents go to marketing.
MER vs ROAS vs blended ROAS
The three metrics differ in what they put above and below the line. Take the same store: $60,000 on Google Ads, $25,000 on paid social and $15,000 for agency, tools and creators.
| Metric | Revenue | Costs | Example |
|---|---|---|---|
| Channel ROAS (Google Ads) | revenue the platform attributes to itself | that platform's ad spend | $280,000 ÷ $60,000 = 4.67 |
| Blended ROAS | total store revenue | all paid media | $500,000 ÷ $85,000 = 5.88 |
| MER | total store revenue | all marketing costs | $500,000 ÷ $100,000 = 5.00 |
Channel ROAS depends on attribution. Each ad platform counts the sales it touched inside its own window, so two platforms often claim the same order. MER can't double count, because it only uses what landed in your store. It also can't tell you which campaign earned the sale.
You need both. Use MER to decide how much to spend in total, and channel ROAS to decide where inside a channel the money goes. What a channel ROAS tells you and what it hides is covered under ROAS meaning. The ROAS formula page runs a single channel from ad account revenue down to profit.
Break-even MER and target MER
A "good MER" depends on your margin. The break-even MER is the point at which marketing eats all the contribution margin it helps create:
| Contribution margin before marketing | Break-even MER | Target MER (10% left) | Target MER (20% left) |
|---|---|---|---|
| 30% | 3.33 | 5.00 | 10.00 |
| 40% | 2.50 | 3.33 | 5.00 |
| 50% | 2.00 | 2.50 | 3.33 |
| 60% | 1.67 | 2.00 | 2.50 |
The example store has a 40% margin and an MER of 5. It keeps 20% of revenue after marketing, exactly the $100,000 from the calculator. With a 30% margin, the same MER of 5 would leave only 10%.
Which target you pick depends on the phase you are in. A brand that wants to grow its customer base can run close to break-even for a few months, as long as those customers reorder and the LTV covers the gap. A brand that has to fund inventory and payroll from its own cash needs the 20% column. Set the target in writing before you set the budget, then check it every month against the store backend.
Break-even MER and break-even ROAS use the same logic at different levels. For a single campaign, use the breakeven ROAS calculator, which also accounts for returns in the ad account.
New customer MER: the growth check
Total MER mixes new and returning customers. A store with a loyal base can post a strong MER while its ads win almost nobody new. New customer MER, often called aMER, splits that out:
Say 2,500 of the example store's customers placed their first order this month, at $80 each. That is $200,000 in new customer revenue and a new customer MER of 2.0. Each new customer cost $100,000 ÷ 2,500 = $40.
| Signal | Total MER | New customer MER | What it usually means |
|---|---|---|---|
| Both steady or rising | 5.0 | 2.0 | Healthy growth |
| Total up, new down | 5.5 | 1.5 | Spend drifts to returning customers and brand searches |
| Total down, new up | 4.5 | 2.4 | You are buying growth, check payback |
A falling new customer MER is the earliest sign that ad spend is paying for sales you would have made anyway.
How to measure MER without fooling yourself
- Revenue from the store backend. Use net sales after returns and cancellations, before sales tax. Platform-reported revenue has no place in MER.
- Every marketing cost. Ad spend on all channels, agency fees, tools, creator and affiliate payouts. Leave one out and MER looks better than your P&L.
- Same period on both sides. Monthly works for the P&L view, a rolling 7 or 28 days for weekly decisions. Compare against the same period last year to strip out seasonality.
- Contribution margin before marketing. Product, shipping, packaging, payment fees and returns. Without it you can't set a break-even.
Harucon measures its guarantee the same way: revenue in your store backend minus returns, at the same ad spend. The details are in the conditions.
Four MER mistakes
- Comparing MER across stores. A 60% margin brand breaks even at 1.67, a 30% margin brand needs 3.33. Benchmarks without margin tell you nothing.
- Chasing a higher MER. Cutting spend almost always raises MER. It can also shrink contribution margin in dollars. Judge the dollars left after marketing.
- Mixing gross and net revenue. Revenue with sales tax and before returns inflates MER. In the example, 25% returns on gross sales would turn a reported MER of 6.67 into the real 5.00.
- Ignoring timing. Spend in a launch month can pay back in the next three. Look at MER over rolling periods, together with the new customer MER.
Marketing efficiency ratio FAQ
What is the marketing efficiency ratio?
The marketing efficiency ratio (MER) is total store revenue divided by total marketing costs. It shows how much revenue your business generates for every dollar of marketing, across all channels.
How do you calculate MER?
Divide total revenue by total marketing costs for the same period. $500,000 in revenue on $100,000 of marketing gives an MER of 5.
What is a good MER?
Any MER above your break-even MER plus the profit you want to keep. Break-even MER is 1 divided by your contribution margin before marketing. At a 40% margin that is 2.5.
What is the difference between MER and ROAS?
ROAS measures one channel or campaign with the revenue that platform attributes to itself. MER uses total store revenue and all marketing costs, so attribution plays no role.
Is MER the same as blended ROAS?
Almost. Blended ROAS divides total revenue by paid media spend only. MER also includes agency fees, tools and creator costs, so it comes out lower.
What is new customer MER?
Revenue from first orders divided by total marketing costs. It shows whether your marketing wins new customers or mostly collects sales from existing ones.
Is your MER above break-even?
On the intro call, Tobias works out your break-even MER with the numbers from your store and shows you which spend doesn't pay off. 5 quick questions, then book straight with Tobias.
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