Unit economicsMetric 13 of 35

CACCustomer Acquisition Cost

What it costs you, fully loaded, to land one new paying customer.

All money spent winning new customers, divided by the number of new customers in the same period. Always fully loaded: salaries, ads, content, tools, attribution noise included.

Formula

CAC = (Sales + Marketing spend) ÷ New Customers acquired

Worked example

Spend $40,000 on sales and marketing in Q1, acquire 80 new customers → CAC = $500.

Benchmark

Months to recover

Strong

< 12 months

Acceptable

12–24 months

Concerning

> 24 months

Why it matters

CAC determines whether your growth is profitable. A low CAC with low LTV is the same problem as a high CAC with high LTV — both can be fine or fatal depending on the ratio. The fastest-growing SaaS companies usually have CAC slightly too high (they're outspending steady-state to grab market share intentionally).

Common mistakes

Excluding salaries from CAC — easily understates by 50–70%.
Using attribution-window CAC instead of period-cost CAC (the latter is what your bank sees).
Not separating blended CAC from paid-CAC — they answer different questions.

Tracked in FlowMRR

Not tracked — FlowMRR reads Stripe, not your ad spend. Pair its ARPU/churn output with your S&M spend to compute CAC.

Track CAC in FlowMRR