Customer Acquisition Cost (CAC)
The total cost of acquiring a new customer, calculated by dividing all sales and marketing spend by the number of new customers acquired in a given period.
CAC is the fundamental unit economic that determines whether your growth is sustainable. It includes all direct costs (ad spend, sales salaries, commissions) and indirect costs (marketing tools, content production, events) divided by new customers acquired. A SaaS company spending $100K on sales and marketing to acquire 50 customers has a CAC of $2,000.
The critical ratio is CAC to LTV (Lifetime Value). A healthy SaaS business targets an LTV:CAC ratio of 3:1 or higher, meaning each customer generates at least three times what it cost to acquire them. Below 1:1, you are losing money on every customer. Between 1:1 and 3:1, the business may be viable but lacks margin for error. Above 5:1, you may be underinvesting in growth and leaving market share on the table.
Reducing CAC is one of the highest-leverage growth activities. AI-powered approaches include predictive lead scoring (focus spend on likely converters), dynamic bid optimization (adjust ad spend in real time based on conversion probability), content personalization (improve conversion rates at each funnel stage), and automated nurturing (reduce the human touch needed to convert). Even small CAC reductions compound as you scale, directly improving profitability and freeing budget for further growth investment.
Related Terms
Growth Loop
A self-reinforcing cycle where each cohort of users generates inputs (data, content, referrals) that attract the next cohort, creating compounding growth.
Churn
The rate at which customers stop using or paying for a product over a given period, typically measured as monthly or annual churn percentage.
Activation Rate
The percentage of new signups who complete a key action (the 'aha moment') that correlates with long-term retention and product value realization.
Product-Led Growth (PLG)
A go-to-market strategy where the product itself drives acquisition, activation, and expansion through self-serve experiences rather than sales-led motions.
Viral Coefficient (K-Factor)
The average number of new users each existing user brings to the product, where a K-factor above 1.0 indicates self-sustaining viral growth.
Net Revenue Retention (NRR)
The percentage of recurring revenue retained from existing customers over a period, including expansion, contraction, and churn — where 100%+ indicates growth without new customers.