Customer Acquisition Economics: The Only Marketing Metric That Matters

From spend to payback

Marketing performance is not measured in reach or impressions but in payback period: how many months of contribution margin it takes to recover the cost of acquiring one customer.

The three numbers to hold together

• CAC: total acquisition spend divided by customers acquired — include salaries and agency costs, not just ad spend.
• Contribution margin per customer: revenue minus variable delivery cost.
• Retention: how long the customer keeps paying.

Reading the result

A payback period under six months usually supports self-funded growth. Beyond eighteen months, growth becomes a financing decision, and the business needs either capital or a cheaper channel.

Channel discipline

Early businesses rarely need many channels. Two channels understood deeply outperform six channels tested casually.