Customer Acquisition Cost
What is Customer Acquisition Cost (CAC)? Definition & Formula
The Definition
Customer Acquisition Cost (CAC) is the total cost of sales and marketing required to acquire one new customer over a given period. It’s calculated by dividing all acquisition-related spend—ad budget, salaries, tooling, commissions—by the number of new customers won in that same window.
The formula is deliberately simple:
CAC = Total Sales & Marketing Spend ÷ New Customers Acquired
The nuance is entirely in what you put in the numerator. A CAC that counts only ad spend will always look flattering—and always be wrong.
In Plain English
CAC is the price tag on a new logo. If you spent $100,000 on sales and marketing last quarter and closed 20 customers, each one cost you $5,000 to acquire—whether they signed a $2,000 deal or a $200,000 one. That gap between what you paid to win them and what they’re worth over their lifetime is the whole game. A business that can’t win customers for less than they’re worth doesn’t have a growth problem; it has a survival problem.
Why CAC Is Meaningless Alone
A $5,000 CAC tells you nothing until you pair it with customer lifetime value. The ratio that matters is LTV:CAC:
LTV:CAC Ratio | What It Signals |
|---|---|
Below 1:1 | You lose money on every customer |
Around 3:1 | The healthy SaaS benchmark |
Above 5:1 | Likely under-investing in growth |
Also watch the payback period—how many months of revenue it takes to recover CAC. Under 12 months is strong for most B2B SaaS; beyond 18 and cash flow gets painful, no matter how healthy the ratio looks on paper.
Common Ways Teams Get CAC Wrong
The most frequent error is a partial numerator: counting ad spend but ignoring salaries, commissions, and tooling. A fully-loaded CAC includes every dollar spent to win the customer. Blending new-business and expansion spend is the other trap—it flatters CAC by crediting acquisition with revenue that actually came from existing customers. The cleanest CAC isolates the cost of net-new logos from the cost of growing the ones you already have. Get the numerator right and CAC becomes a decision-making tool; get it wrong and it quietly disguises an unprofitable growth model as a healthy one.