Free calculator
MER calculator
Enter total store revenue and total ad spend for the same period. You get MER, ad spend as a share of revenue, new-customer MER, and how the platforms’ own revenue figures compare with what the store sold.
Results Example figures. Change any field.
MER
Ad spend as a share of revenue
New-customer MER (aMER)
Platforms claim this share of revenue
The formula
How it’s calculated.
MER = total revenue ÷ total ad spend
Worked example
A store with $120,000 in revenue and $30,000 of ad spend across every channel has an MER of 120,000 ÷ 30,000 = 4.00×, so ads cost 25% of revenue. $50,000 of that revenue came from new customers, so new-customer MER is 1.67×. If Meta, Google and TikTok together report $150,000, they are claiming 125% of what the store sold.
MER vs ROAS: how to calculate both →Why MER can’t be double counted.
MER uses the revenue in your store and the spend on your invoices, so no attribution model sits between them.
That makes it the check on platform ROAS: if every channel’s ROAS looks strong but MER is falling, the platforms are crediting each other’s sales.
MER and new-customer MER.
Total MER includes repeat orders that would arrive without ads. New-customer MER (aMER) divides only first-time buyers’ revenue by ad spend, so it shows what ads do to grow the customer base.
A rising MER with a falling aMER usually means returning customers are carrying the number.
See how Upstack Attribution reports it →More calculators
Related calculators.
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ROAS calculator
Return on ad spend, your break-even ROAS, and the gap between platform and Shopify revenue.
ROAS = revenue from ads ÷ ad spend
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Contribution margin calculator
CM1 to CM4 in dollars and as a share of net revenue.
CM3 = net revenue − product costs − shipping, fulfillment and fees − marketing
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CAC calculator
Paid and fully loaded CAC, and how many orders it takes to earn it back.
CAC = (ad spend + other acquisition costs) ÷ new customers
Questions
MER questions.
How do you calculate MER?
Divide total revenue for a period by total ad spend across every channel for the same period. $120,000 in revenue on $30,000 of ad spend is an MER of 4.
What is the difference between MER and ROAS?
MER uses all revenue and all ad spend, with no attribution. ROAS uses the revenue one platform attributes to its own ads. MER tells you whether marketing pays overall; ROAS helps you compare channels.
What is a good MER?
One that leaves profit after product, shipping, fees and ads. If your margin before ads is 55%, an MER of 1.82 breaks even, and anything above it leaves contribution margin to cover fixed costs and profit.
What is aMER?
Acquisition MER: revenue from new customers divided by total ad spend. It leaves out repeat purchases, so it shows how efficiently ads bring in first-time buyers.
Get these numbers from your own store.
Upstack Attribution reports ROAS, MER, new-customer CAC, LTV and CM1 to CM4, reconciled against the revenue in Shopify.
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