Customer Acquisition Cost: What It Costs to Win a Customer

The mental model

Customer Acquisition Cost (CAC) is the total cost of sales and marketing divided by the number of new customers acquired in a given period. It's the price tag for winning a single customer. If you spend 10,000 on marketing in a month and get 100 new customers, your CAC is 100. The goal is to keep this number as low as possible while acquiring high-value customers.

How it works

The basic formula is: CAC = (Total Sales Costs + Total Marketing Costs) / (Number of New Customers Acquired). It's crucial to define the time period consistently, such as monthly or quarterly. A simple calculation includes all expenses from that period, like ad spend, salaries of sales and marketing teams, and software subscriptions. More advanced models might account for the time lag between spending money and acquiring a customer, attributing costs from a previous period to customers acquired in the current one.

When to use it

CAC is essential for assessing the health of a business model, primarily by comparing it to Customer Lifetime Value (LTV). A healthy LTV:CAC ratio is often cited as 3:1 or higher, meaning the customer generates at least three times more value than they cost to acquire. It's also used to compare the efficiency of different marketing channels. If Google Ads yields a 50 CAC and LinkedIn Ads a 100 CAC, you can make informed decisions about where to allocate your budget.

When not to use it

Do not use CAC in isolation. A low CAC is not inherently good if it brings in low-value customers who leave quickly. Conversely, a high CAC can be perfectly acceptable if it acquires customers with a very high LTV. Be cautious applying it to very early-stage companies where marketing is experimental, or in businesses with extremely long sales cycles where a simple monthly calculation would be misleading.

One canonical example

A software company spends 10,000 on ads in Q1. The quarterly salaries for their marketing and sales team total 50,000. They acquired 500 new customers in Q1. Their total acquisition cost is 10,000 + 50,000 = 60,000. Their CAC is 60,000 / 500 customers = 120 per customer. If their average customer has an LTV of 400, their LTV:CAC ratio is 3.33:1, indicating a sustainable business model.