MER Calculator

Measure all marketing against all revenue, and find the MER you need to break even or hit a profit target.

Your numbers

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Total store revenue

All channels for the period, excluding tax.

Paid ad spend

Other marketing costs

Influencers, affiliates, agencies, email and SMS tools.

Contribution margin before marketing

Revenue minus product, shipping, fulfilment and payment costs, as a %.

Profit you want (% of revenue)

Your result · updates as you type

Marketing efficiency ratio (MER)

5.45x

Every $1 spent on marketing sits against $5.45 of total revenue. Marketing is 18.3% of revenue.

Break-even MER: 2.50x
MER for 10% profit: 3.33x
Contribution after marketing: $26,000

You're above your target MER, so there's room to test more spend. Watch that MER doesn't fall faster than revenue grows.

Breakdown

Revenue: $120,000
Contribution before marketing: $48,000
Total marketing: −$22,000
Contribution after marketing: $26,000
Most you could spend at break-even: $48,000
Most you could spend for 10% profit: $36,000

What MER measures

Marketing efficiency ratio compares total store revenue with total marketing spend across every channel. It ignores attribution completely, which is its strength: it can't be inflated by platforms each taking credit for the same sale.

MER = total revenue ÷ total marketing spend

On its own, an MER of 5x means nothing until you know your margin. That's why the calculator works out the two numbers that matter:

Break-even MER = 1 ÷ contribution margin before marketing

Target MER = 1 ÷ (contribution margin before marketing − profit you want)

Example

Revenue: $120,000
Total marketing: $22,000
Contribution margin before marketing: 40%

MER = 5.45x. Break-even MER is 2.5x, and a 10% profit target needs 3.33x, so this store has room to spend more.

Using MER alongside ROAS

MER for the budget, ROAS for the campaigns. Decide total spend by MER, then use platform ROAS to split it between campaigns.
Track it weekly. A falling MER while revenue grows is normal when scaling; a falling MER with flat revenue means spend is being wasted.
New-customer MER (revenue from first orders ÷ spend) is stricter and shows whether marketing is actually finding new buyers.

Questions people ask

What counts as marketing spend?

All of it: paid ads, influencer fees, affiliate commissions, agency retainers and the cost of email and SMS tools. The point of MER is to leave nothing out.

What's a good MER for ecommerce?

Whatever clears your target MER. A store with 60% contribution margin can be profitable at 2.5x; one with 30% needs more than 3.3x just to break even.

Is MER the same as blended ROAS?

Nearly. Blended ROAS usually counts only paid ad spend; MER includes every marketing cost. MER is the stricter number.

Where does contribution margin come from?

Revenue minus product, shipping, fulfilment and payment costs, as a percentage. The contribution margin calculator works out your CM2, which is the number to use here.

Last reviewed 29 September 2026.