What CAC means
CAC stands for customer acquisition cost. It is the total amount you spend on sales and marketing to win one new customer. The formula is short:
CAC = total sales and marketing spend / new customers acquired
If you spend $5,000 across ads, apps, and creative in a month and that brings in 200 new customers, your CAC is $25. Unlike CPA, which looks at a single campaign, CAC takes everything into account: every ad channel, every tool, every dollar that went into acquisition. It is a business-level number, not a campaign-level one.
How to read your CAC
CAC means little on its own. It only becomes useful next to the lifetime value (LTV) of a customer, which is how much profit a customer brings over the whole time they buy from you. The relationship people watch is the LTV to CAC ratio:
- LTV to CAC around 3:1 is the common healthy benchmark. Each customer is worth roughly three times what they cost to acquire.
- LTV to CAC near 1:1 means you barely recover acquisition cost, leaving nothing for overhead or profit.
- A very high ratio can mean you are under-investing in growth and could afford to spend more to acquire customers faster.
Because stores with strong repeat purchase rates can afford a higher CAC, this is where retention and acquisition meet. A first sale that breaks even is fine if the second and third sales are pure margin.
CAC versus CPA
CPA and CAC use the same shape of formula, which is why they get confused. The difference is scope:
- CPA is ad spend divided by conversions, for one campaign or channel.
- CAC is all sales and marketing spend divided by new customers, for the whole business.
Use CPA to judge an ad set. Use CAC to judge whether the business can grow profitably.
A worked example
Over a quarter:
- Total sales and marketing spend: $30,000
- New customers acquired: 750
- CAC = 30,000 / 750 = $40
It cost $40 to win each customer. If a customer is worth $120 in profit over their lifetime, your LTV to CAC ratio is 3:1, right at the healthy benchmark. If they are only worth $50, the model is too tight and you need cheaper acquisition or more repeat revenue.
Estimate a competitor's economics
You cannot see a rival's ad spend, but you can read their pricing and product mix to estimate their margins and acquisition pressure. Koala Inspector is the Chrome extension that surfaces the live ads, best-selling products, and pricing on any Shopify store. See the full toolkit in our Shopify spy tools list.
