CAC Calculator: Find Out How Much It Costs You to Get  a Customer

How to use this CAC Calculator

Enter your total marketing spend and the number of unique customers acquired during any time period. The calculator shows your average cost per customer – a starting point for understanding acquisition economics.

What is Marketing CAC? (Customer Acquisition Cost)

CAC measures how much marketing spend it takes to acquire one paying customer. In its simplest form: marketing spend ÷ total customers.

Example: £10,000 spend ÷ 10 customers = £1,000 per customer.

You can expand this to include sales team costs, software, and other overheads. Marketing CAC specifically isolates marketing/ad spend divided by customers acquired.

When to use CAC

Beyond ROAS and MER, CAC tracks your actual cost per customer. While you’re optimizing campaigns (cost per lead, cost per click, CPM), CAC forces the conversation beyond marketing metrics into business profitability.

This is where other departments matter. Marketing doesn’t exist in isolation – customer retention, service quality, and product value all determine whether your CAC makes financial sense.

What’s break-even CAC?

Using the £1,000 example: if your customer spends £100/month, you need 10 months of retention to break even. Month 11+ is profit.

This connects CAC to monthly recurring revenue and lifetime value. Your retention team, customer service, and loyalty programs directly impact whether marketing spend pays off. CAC forces everyone to care about keeping customers, not just acquiring them.

Limitations of CAC

Time Lag: CAC assumes costs and acquisitions happen in the same period. Reality: a January campaign might convert in March or April. Track at 30, 60, and 90-day intervals for accuracy.

Ignores Customer Value: Low CAC means nothing if customers don’t generate profit. £50 CAC for a £40 customer is a structural problem. Always view CAC against lifetime value.

CAC is an average: It hides channel-specific costs. SEO customers might cost £20 while paid social costs £200. Some customers are more valuable than others. Daily cost per lead fluctuates wildly – CAC smooths this into a single number that can obscure important patterns.