Define the cost boundary
Decide which media, creative, tools, sales and team costs belong to acquisition. Some costs also support retention or brand activity, so document allocation assumptions instead of pretending every expense has one obvious category.
Define a new customer using the business record, not merely a platform conversion. A lead, trial or returning buyer is not equivalent to a new paying customer.
Build the calculation
- List the cost categories and their data owners.
- Choose an eligible customer definition and period.
- Account for the delay between acquisition work and purchase.
- Present media-only and broader measures separately when useful.
- Note allocation assumptions and exclusions in the report.
A period ratio can be informative without being a precise cohort cost. Long sales cycles may require a more careful connection between spending and resulting customers.
Worked example: two valid measures
Illustrative example: a business spends 6,000 units on media and includes 10,000 additional units of acquisition-related costs. It gains 80 eligible new customers under the chosen period definition. Media-only cost is 6,000 / 80 = 75; the broader measure is 16,000 / 80 = 200.
Neither calculation is improved by hiding its scope. The right measure depends on the decision, and both need customer quality and later value for interpretation.
Reporting table
| Measure | Useful for | Limitation |
|---|---|---|
| Media-only CAC | Campaign spending decisions. | Excludes other acquisition effort. |
| Fully loaded CAC | Wider operating economics. | Requires cost-allocation assumptions. |
| Cost per lead | Early acquisition diagnosis. | Does not identify paying customers. |
| Cohort-based view | Connecting acquisition and later value. | Needs reliable records and sufficient maturity. |
Avoid convenient denominators
Do not include repeat purchases as new customers to make acquisition cost appear lower. Also inspect whether promotions attracted customers who quickly refund, refuse delivery or leave. A cheaper new-customer count is not automatically better economics.
Should founder time be included?
For an operating economics view, its role should be acknowledged. The exact allocation depends on the purpose; document the assumption rather than implying unpaid effort has no cost.
Is lower CAC always better?
No. Customer value, margin, retention and available demand matter. A higher acquisition cost can support a more valuable customer relationship.
Put this into practice
Write your CAC formula with every cost category and the exact customer denominator. Show the narrower media measure beside it if the team uses both for different decisions.
Related foundation: CAC vs ROAS: which metric should guide your marketing budget?. How these guides are prepared.
Ayoub Mouhachtt
Growth & performance marketing. Explore the portfolio and working background.
Related portfolio work: Etsy & Shopify. The worked examples in this guide are illustrative and are separate from the portfolio’s project evidence.