Blended CAC and MER calculator
Enter your marketing spend, revenue, and new customers to calculate blended CAC, paid CAC, and MER (marketing efficiency ratio).
The formulas
- Blended CAC = total marketing spend divided by total new customers.
- Paid CAC = paid media spend divided by customers attributed to paid media.
- MER = total revenue divided by total marketing spend; some teams call this blended ROAS.
Worked example
Spend $50,000, revenue $200,000, 400 new customers: blended CAC $125, MER 4.00x.
Of that, $40,000 was paid media and 250 customers were attributed to paid: paid CAC $160.
Paid CAC above blended CAC is normal; organic and returning-customer demand lowers the blended number.
When blended numbers mislead
- An organic or seasonal surge can lower blended CAC while paid efficiency gets worse.
- MER uses revenue, not margin. A high MER on low-margin products can still lose money; compare against contribution margin.
- Revenue from returning customers raises MER without any new acquisition.
Calculate it from your real numbers
Margin, part of the Bellaso suite, calculates blended CAC and MER from your ad accounts and accounting books, so the numbers match what finance reports.