Customer Acquisition Cost
Also: CAC, Cost of Customer Acquisition, Acquisition Cost
Customer Acquisition Cost (CAC) is the total sales and marketing spend divided by the number of new customers gained in a period. It measures how efficiently you grow.
What it is
Customer Acquisition Cost (CAC) is the average amount a business spends to acquire one new paying customer. It is calculated by dividing the total cost of sales and marketing over a period by the number of new customers acquired in that same period.
The basic formula is:
CAC = (Total Sales & Marketing Costs) / (Number of New Customers Acquired)
Costs typically include advertising spend, salaries and commissions for sales and marketing teams, agency fees, software and tooling, and content production. The cleaner and more complete the cost inputs, the more trustworthy the number.
Why it matters
CAC is a core efficiency metric that links spending to growth. It matters because:
- It tells you whether your go-to-market motion is sustainable.
- It is the foundation for unit economics when compared against customer value.
- It guides budget allocation across channels and campaigns.
- Investors and boards use it to judge the health of a growth model.
A low CAC on its own is not the goal. What matters is CAC relative to the revenue and profit a customer generates over time.
How it is used in practice
CAC is rarely viewed alone. Teams pair it with the LTV:CAC ratio (Lifetime Value divided by CAC). A common benchmark is a ratio of 3:1 or higher, meaning each customer returns at least three times their acquisition cost.
Another key companion metric is the CAC payback period: how many months of gross margin it takes to recover the cost of acquiring a customer.
Practical applications include:
- Channel comparison: measuring CAC per channel (paid search, social, events, outbound) to shift budget toward efficient sources.
- Blended vs paid CAC: blended includes organic customers, paid isolates spend-driven acquisition.
- Cohort analysis: tracking CAC trends over quarters to spot rising costs early.
Concrete example
A SaaS company spends $40,000 on marketing and $60,000 on sales in one quarter, totaling $100,000. It acquires 250 new customers.
CAC = $100,000 / 250 = $400 per customer.
If each customer pays $50 per month at 80% gross margin ($40 margin per month), the payback period is $400 / $40 = 10 months. If average customer lifetime is 36 months, lifetime margin is $1,440, giving an LTV:CAC of 3.6:1, a healthy result.
Frequently asked questions
What exactly does Customer Acquisition Cost measure?
Customer Acquisition Cost (CAC) measures the average spend required to win one new paying customer: total sales and marketing costs for a period divided by the number of new customers acquired in that same period. Costs normally include advertising, salaries and commissions, agency fees, software and content production. The metric links money spent to growth actually delivered.
How do you calculate CAC, with a worked example?
CAC = total sales and marketing costs divided by new customers acquired. If a SaaS company spends $40,000 on marketing and $60,000 on sales in a quarter ($100,000 total) and signs 250 new customers, CAC is $400 per customer. The quality of the number depends entirely on how completely you load the cost side.
Is a low CAC always a good sign?
No. A low CAC means nothing on its own; what counts is CAC compared with the revenue and margin a customer generates over their lifetime. A high CAC can be perfectly healthy if customers stay long and pay well, and a low CAC can still destroy value if they churn quickly.
What is the difference between the LTV:CAC ratio and the CAC payback period?
LTV:CAC compares the total value a customer brings against what they cost to acquire, with 3:1 or higher often used as a benchmark. CAC payback answers a different question: how many months of gross margin are needed to recover the acquisition cost. The first speaks to profitability, the second to cash timing.
When should I look at blended CAC rather than paid CAC?
Blended CAC includes customers who arrived organically and shows the real overall cost of growth, which is what boards and investors usually want to see. Paid CAC isolates spend-driven acquisition and is the right lens for judging a channel or campaign. Tracking CAC per channel and by quarterly cohort is how teams spot rising costs before they hurt.