What Is Customer Acquisition Cost?
Customer acquisition cost (CAC) is the total sales and marketing spend needed to win one new customer. Pair it with lifetime value to assess whether your growth is commercially sustainable.
Key Takeaways
- CAC is the total sales and marketing spend required to win one new customer.
- CAC should always be evaluated against customer lifetime value (LTV) to assess commercial viability.
- An LTV:CAC ratio of 3:1 or above is generally considered healthy.
- Reducing CAC or increasing LTV are the two levers for improving unit economics.
How to calculate customer acquisition cost
Customer acquisition cost (CAC) is calculated by dividing total sales and marketing expenditure in a period by the number of new customers acquired in that period. Sales and marketing expenditure should include salaries, commissions, advertising spend, agency fees, software costs, and any other costs directly attributable to winning new business. If you spent £120,000 on sales and marketing in a quarter and acquired 40 new customers, your CAC is £3,000. For SMEs, it is important to be consistent about which costs are included — including too little understates CAC; including shared overhead inflates it.
CAC by channel and segment
A blended CAC across all channels and customer types is a starting point. The more valuable analysis is CAC by acquisition channel (paid search, referral, outbound, events) and by customer segment (size, industry, product). A customer acquired through referral may cost £500 to win; the same profile of customer acquired through paid advertising may cost £4,000. This information drives budget allocation: channels with low CAC and high LTV deserve more investment; channels with high CAC and low retention deserve scrutiny. Segment-level CAC also reveals whether your most valuable customer types are cheap or expensive to acquire.
The LTV:CAC ratio
CAC in isolation is meaningless — it must be evaluated against the lifetime value (LTV) of the customers you are acquiring. LTV is the total gross profit expected from a customer over the duration of the relationship. An LTV:CAC ratio of 3:1 is a commonly cited benchmark for sustainable unit economics: you generate £3 of gross profit for every £1 spent acquiring a customer. A ratio below 2:1 suggests the business is spending too much to acquire customers relative to what they generate. A ratio above 5:1 may indicate underinvestment in growth — the business could afford to spend more on acquisition to grow faster.
Improving CAC over time
CAC typically falls as a business matures, for two reasons. First, brand awareness and reputation reduce the cost of attracting prospects. Second, a refined go-to-market motion — better targeting, sharper messaging, clearer ICP — reduces wasted spend. For SMEs, the fastest routes to reducing CAC are: investing in referral programmes that turn happy customers into a low-cost acquisition channel; improving conversion rates at each stage of the funnel so more of the marketing spend translates into wins; and sharpening the ideal customer profile to eliminate spend on segments that rarely convert or retain poorly.