Customer acquisition cost: what a customer really costs you to win

Customer acquisition cost is the total spent on winning customers in a period, divided by the number of customers won. Both halves of that sentence hide decisions, and the decisions are where the number becomes either useful or comforting.

The flattering version counts only advertising spend and every new name in the database. The honest version counts everything spent to make acquisition happen — including the people doing it — and only customers who actually paid. The gap between the two is frequently a factor of three, which is enough to make a losing channel look profitable.

Calculating it honestly

1. Take a period long enough to matter — a quarter for most small businesses, a month if volume is high.
2. Add up everything spent on winning customers: advertising, content, tools, agency fees, commissions, and the salary cost of the people doing sales and marketing. The salaries are what people leave out and are usually the largest line.
3. Count new paying customers in that period. Not signups, not trials, not leads. Paying.
4. Divide. That is blended customer acquisition cost — the number for the business as a whole.
5. Then split it by channel, which is where the decisions live. A blended figure of 400 can be one channel at 150 and another at 900, and the average tells you to do more of both.

Include the salaries. A two-person business spending 5 000 a month on ads and half of somebody's time is not acquiring customers for the price of the ads, and calculating as if it were is how a channel that loses money survives for a year. If the objection is that the person would be paid anyway, the answer is that their time has an alternative use, and the arithmetic exists to compare uses.

Reading the number

• Against what a customer is worth. The comparison with customer lifetime value is the only thing that makes an acquisition cost good or bad in itself.
• Against payback period — how many months of margin it takes to recover the cost. For a small business without funding, this matters more than the ratio, because payback is what the bank account experiences.
• By channel, always. Aggregate acquisition cost is a reporting number; the per-channel figure is a decision.
• Over time. A rising cost at flat volume is the earliest sign that a channel is saturating.
• Against the effort of retention. Keeping an existing customer is usually cheaper than winning a new one, which is the argument behind churn rate.

The LTV to CAC ratio, and its limits

The widely quoted target is a lifetime value at least three times acquisition cost. It is a reasonable rule of thumb for a funded software business and a poor one for everybody else, because lifetime value is a projection and acquisition cost is money that already left. A ratio of three built on an optimistic five-year lifetime can still bankrupt a business that has to pay the cost this month and collects the value over years. For a small business the more useful pair is payback period and gross margin: how long until the cost is recovered, and how much of each sale is available to recover it.

Bringing it down

1. Improve conversion before increasing spend. The same traffic converting better lowers acquisition cost immediately and permanently, which is the case for conversion rate optimization.
2. Cut the worst channel entirely rather than optimising it. Small businesses rarely have the volume to optimise a bad channel into a good one.
3. Ask where customers actually came from, in a field on the record, rather than inferring it. Attribution tooling is beyond most small budgets; asking is not.
4. Lean on referrals and repeat business, which arrive at close to zero cost and are systematically under-invested in.

Where the numbers live

Ettex CRM holds where customers came from and what they bought, which is what makes a per-channel figure possible at all; the spending side comes out of Ettex Books; and the arithmetic sits in Ettex Sheets where you can rerun it by channel and by quarter.

Being clear: there is no attribution model, no ad platform integration and no automatic cost import. The source of each customer is a field somebody fills in, and for most small businesses a recorded answer to how did you hear about us beats an inferred one from a tool nobody has configured.