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MER and blended CAC calculator

Use the store's own revenue and your total spend. MER and blended CAC need no attribution, so no platform can inflate them.

Stock photos and example labels, not customers.

Add up what each ad platform reports.

Example presets use made-up numbers.

How it is calculated

MER = store revenue / total marketing spend. Blended CAC = total marketing spend / new customers. Average order value = revenue / orders. Platform overlap = revenue claimed by platforms / store revenue.

Example with made-up numbers: 80,000 revenue and 20,000 spend give a MER of 4.0. With 500 new customers, blended CAC is 40. If the platforms together claim 120,000, they claim 1.5 times the revenue the store booked.

How to read the result

  • Track MER month by month with the same definition of revenue and spend.
  • Compare blended CAC with the contribution of a first order.
  • A platform overlap above 1.0 means platforms count some orders more than once or use wider windows.

Keep the inputs honest

Convert currencies to one rate, align time zones, decide whether revenue is net of refunds, and include every channel in spend. If a figure is unknown, leave the field empty instead of entering zero.

Related terms

MERBlended CACPlatform ROASCPA

Read next

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MER vs ROAS: which number an agency should report

Platform ROAS tells you how an ad platform scores itself. MER tells you how the business did. A client review needs both, clearly labelled.

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Blended CAC: what it is and when to use it

When platforms disagree about who deserves credit, blended CAC answers a plainer question: what did a new customer cost us in total?

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Why your MER is wrong: currencies, time zones and refunds

Most disagreements between a store and its ad reports are not strategy problems. They are mismatches in how two data sets were cut.

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Questions about this tool

Why does MER ignore attribution?

MER divides total revenue by total spend, so it needs no decision about which ad gets credit. It is less precise about channels, but it cannot be inflated by overlapping platform claims.

What counts as a new customer?

A person ordering for the first time, taken from the store's order data. Do not take it from an ad platform.

Is my data stored?

No. The calculation runs in your browser and nothing is sent anywhere.

Built for shop owners, creators and agencies. Stock photos, not customers.

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