Customer acquisition cost (CAC)

CAC turns marketing activity into one practical number: what it costs to get a paying customer through the door. It is broader than cost per lead or cost per click, which only measure steps along the way. A campaign can have cheap leads and still have an expensive CAC if few of those leads buy.

CAC is only meaningful next to what a customer is worth. A CAC of 200 is excellent for a customer who spends thousands over several years and ruinous for one who buys a single 50 item. That is why it is usually read alongside customer lifetime value.

How it works

The basic formula is CAC = total sales and marketing costs ÷ number of new customers acquired. Costs include ad spend, agency and freelancer fees, marketing software, content production, event costs and the share of staff salaries spent on marketing and sales. Count only new customers, not repeat purchases from existing ones.

Many businesses also calculate CAC per channel, such as paid search or social, by dividing that channel's costs by the customers it brought. This depends on attribution, so channel CAC is an estimate, while the overall figure is simpler and harder to distort. Some include only paid media costs and call the result paid CAC; whichever version you use, say which costs it includes.

Timing creates edge cases. If a business sells with a long decision period, money spent in one month may produce customers months later, so comparing a single month's costs with the same month's customers misleads. Using a quarter or a rolling period smooths this. To work out your own CAC, total last quarter's sales and marketing costs from your accounts, count new customers from your sales records over the same quarter, and divide.

Example

A home-cleaning company spends, in one quarter, 3,000 on ads, 900 on a freelance marketer, 300 on software and an estimated 1,800 on the owner's and a coordinator's time handling sales calls, a total of 6,000. It gains 75 new regular customers in the quarter, so its CAC is 6,000 ÷ 75 = 80.

Split by channel, customers from referrals cost very little to acquire, while those from paid social cost far more than the average. The owner checks how long customers stay: the average regular customer keeps booking for well over a year and brings in many times 80 in profit over that time, so paid social still pays, but a small referral reward is likely to be the better next investment.

Why it matters for your business

CAC tells you whether growth is affordable. If it costs more to win a customer than that customer will ever bring in profit, more marketing makes the problem bigger, not smaller. Tracking it also shows when a channel is getting more expensive, which often happens as competition rises. The trade-off is precision: honest CAC includes time and overheads that are hard to measure, but leaving them out makes growth look cheaper than it is. Recalculating it every quarter with the same rules shows whether your marketing is becoming more or less efficient over time.

Common mistakes

• Counting only ad spend and ignoring fees, software and staff time.
• Dividing by all customers, including repeat buyers, which makes CAC look lower than it is.
• Judging CAC without comparing it with what a customer is worth over time.
• Comparing one month's spend with the same month's customers when sales take months to close.

Questions people ask

How do you calculate customer acquisition cost?

Add up all sales and marketing costs for a period, including ads, fees, software and relevant staff time, and divide by the number of new customers won in the same period. If you spent 5,000 and gained 50 new customers, your CAC is 100.

What is the difference between CAC and cost per lead?

Cost per lead measures what you pay for each enquiry or sign-up, whether or not that person ever buys. CAC measures what you pay for each actual new customer. When both use the same costs, CAC is higher than cost per lead whenever some leads do not buy, and it is closer to what matters.

How can I lower my customer acquisition cost?

Common ways are improving conversion on your website, so more visitors become customers, following up leads faster, cutting channels that bring poor-quality leads and encouraging referrals from existing customers. Raising conversion often lowers CAC without spending any less on marketing.