What is CAC?

CAC stands for Customer Acquisition Cost — the average amount you spend to win one new customer. That figure includes everything that went into attracting and closing them: ads, sales time, campaigns, tools and other marketing spend tied to bringing someone on board.

Think of it like fishing. CAC is the cost of the rod, the bait, the fuel for the boat and the hours you spent waiting — all divided by the number of fish you actually caught. Catch few fish with expensive gear and each one costs a fortune. Catch many cheaply and each one is a bargain. Customers work the same way.

CAC rarely tells you much on its own. It only becomes meaningful when you compare it to LTV — how much that customer is worth over their lifetime. If it costs more to acquire a customer than they ever pay back, you lose money on every new sale, no matter how fast you grow.

Why does CAC matter for your business?

CAC shows whether your growth is genuinely profitable or just looks good on paper. Two companies can grow at the same pace, but the one acquiring customers cheaply makes money while the one overpaying bleeds cash. Tracking CAC helps you put marketing budget where it actually works.

A common benchmark is that customer lifetime value (LTV) should be at least three times CAC. If CAC is too high relative to what customers return, that is a signal to cut acquisition cost or increase customer value.

CAC in practice

Say you spend £1,000 on ads in a month and those ads bring in 20 new customers. Your CAC is £50 per customer. If each customer is worth £300 over time (LTV), that is a strong business. If they are only worth £40, you are losing money on every new customer — and something has to change.

For a small business, this is often the difference between healthy and unhealthy growth. Measuring CAC shows you which channels deliver cheap customers and which burn budget. Referrals from happy customers might be nearly free, while a particular ad channel could be expensive — and then you know where to invest.