Customer acquisition cost: what does a new customer really cost?
The question every owner asks after a season of advertising: how much did each new customer actually cost me?
Customer acquisition cost (CAC) is the average amount a business spends to win one new customer over a given period. You add up marketing and sales spending, including staff time, and divide it by the number of new customers gained. It is not the same as the cost per conversion shown in ad platforms.
In short
- Basic formula: spending to attract customers ÷ new customers won.
- Google Ads CPA measures the cost of a tracked action, not necessarily a paying customer.
- Include staff time, not just advertising invoices.
- In Quebec French, the preferred term is coût de conversion du client.
What goes into customer acquisition cost?
On top: everything you spent to attract new customers during the period. That means ads, flyers, trade shows, referral fees, software, and the hours staff spent prospecting or doing estimate visits. On the bottom: only new customers, not returning ones.
Use a period long enough for spending to turn into customers. For a service business, a quarter usually says more than a single week.
How does Quebec French name this metric?
Quebec's Grand dictionnaire terminologique lists customer acquisition cost and CAC as English terms and recommends coût de conversion du client in French. It defines it as the cost of an advertising campaign, found by comparing its operating costs with the number of prospects converted into actual customers [1].
The entry discourages the literal calque coût d'acquisition du client, because in French you acquire goods or skills, not people. It also notes that for social media campaigns, the number of connections made often replaces the number of customers converted [1].
How do CAC, CPA and cost per click differ?
| Metric | What is divided | What it tells you |
|---|---|---|
| Cost per click | Ad spend ÷ clicks | The price of one visit from an ad |
| CPA (cost per action) | Ad spend ÷ tracked conversions | The price of a request, call or booking |
| CAC | All acquisition spending ÷ new customers | The real price of a customer who paid |
A conversion tracked in an ad tool isn't always a new customer: a request may never become a job.
How does Google Ads handle cost per conversion?
With Target CPA bidding, the advertiser sets the average cost per conversion it wants, and Google Ads sets bids to get as many conversions as possible at that average. Some conversions will cost more than the target and some less [2].
That CPA depends on how a conversion is defined, and Google notes one click can produce several conversions [3]. To get from CPA to CAC, you need to know how many of those conversions became paying customers, which is your conversion rate all the way to a signed job.
How do you calculate CAC for a small service business?
Which mistakes distort CAC?
- Counting only the ad invoice and forgetting the hours spent on estimate visits.
- Dividing by every customer served, regulars included, which makes CAC look tiny.
- Comparing CAC with the first invoice only, ignoring customer lifetime value.
- Blending channels: an overall CAC often hides one profitable channel and one losing one.
- Calculating it once a year instead of tracking it as a KPI on a dashboard.
How should you read a CAC figure?
A CAC is neither good nor bad on its own; it only means something next to what a customer brings in. An annual maintenance client who stays for years can justify a higher CAC than a one-off job. Always set CAC beside the margin that customer leaves in your revenue.
Also check the payback period: how many visits does it take for the margin on that customer to cover what it cost to win them?
Does Pilotiko calculate CAC?
Pilotiko's internal reports track bookings and revenue, which supplies part of the data you need. Keep each customer's source in your CRM so new customers can be counted by channel. Ad spending can be planned and entered manually; Pilotiko does not run ads.
Frequently asked questions
What is the customer acquisition cost formula?
Add up everything spent to attract new customers during a period, then divide by the number of new customers won in that same period. Include staff time, not just advertising.
What is the difference between CAC and CPA?
CPA divides ad spend by tracked conversions such as requests or calls. CAC divides all acquisition spending by new customers who actually bought.
Should the owner's time count in CAC?
Yes, if the owner spends hours on estimates or prospecting. Otherwise CAC looks lower than it really is, especially in a small company.
How can I lower my CAC?
Start by improving how many requests turn into jobs, cut channels that cost money without producing customers, and encourage referrals. Measure each change separately.
What is CAC called in Quebec French?
Quebec's language office recommends coût de conversion du client and discourages coût d'acquisition du client. The acronym CAC is still widely understood.
Sources
- Office québécois de la langue française (Vitrine linguistique), coût de conversion du client (GDT) (accessed on October 15, 2026).
- Aide Google Ads, About Target CPA bidding (accessed on October 15, 2026).
- Aide Google Ads, Conversion rate: Definition (accessed on October 15, 2026).
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Conversion rate explained for service businesses: the formula, the stages worth tracking, a renovation example from Sherbrooke and the traps that skew it.
Customer lifetime value: what is a customer worth over time?
Customer lifetime value explained: the simple formula, the margin-based version, a heat-pump maintenance example and what Google Analytics can predict.
What is revenue, and how do you calculate it?
What revenue means for a small business: sales and services for a period, gross versus net, a GST and QST example for a Quebec service company, common mix-ups.
What is a KPI (key performance indicator)?
What a KPI is, how to derive one from a business goal, formulas for a service company, a worked month of numbers and the traps to avoid when picking them.