CAC: what customer acquisition cost is and how to calculate it

Marcel GarciaUpdated Sep 25, 2026

CAC (customer acquisition cost) is what it costs you to win a new client: everything you spend on acquisition in a period, divided by the new clients that spend brought in. It is calculated per channel and read next to LTV; on its own, it says nothing.

It is the number that separates marketing that works from marketing that only looks like it works. A campaign can bring a hundred leads and no profitable client; a channel can look expensive and be the cheapest in the system once you measure what each client costs rather than each click. This guide explains how to calculate it without cheating, which LTV:CAC ratio makes a business scalable, and how to lower it without touching the price.

It is signed by Marcel Garcia, founder of HAKI. The examples with round numbers are just that, examples; the real figures are only the ones a case page publishes.

How CAC is calculated

The formula is simple: CAC = acquisition spend in the period divided by new clients in the period. The hard part is deciding what goes in the numerator. Everything that exists to acquire goes in: media spend (Google Ads, Meta Ads, LinkedIn), tools (CRM, automation, data), the hours of whoever runs it, inside or outside the company, and the share of the website and content that exists to acquire. If you only count the ads, you have a channel's CPA, not the business's CAC.

The denominator is clients, not leads or appointments: people who have paid. And the period has to respect the sales cycle: if three months pass between first contact and signature, January's spend is compared with March or April's clients, not January's. A business that sells something expensive almost always has a long cycle, and that is where a monthly CAC misleads.

Calculate it per channel as well as in total. The total hides the channel that loses money behind the one that makes it. In a mature system, organic (SEO, referrals, brand) lowers the average CAC year after year while ads hold it up in the short term.

How it is usually calculated and how to do it right

Six decisions that change the number. Almost every CAC we are shown on a first call gets three of them wrong.

	How it is usually done	How to do it right
What spend counts	Only the ads	Media, tools, hours and the share of website and content that exists to acquire
What is divided	Leads or appointments	Clients who have paid
Period	The calendar month	The month of the spend against the clients that spend brought, per the sales cycle
Level of detail	One total number	Per channel, with the total as a check
What it is compared with	With last month's CAC	With LTV: the margin a client leaves over the whole relationship
When it is looked at	At the end of the campaign	Every week, on the same page as new clients and the pipeline

An example with round numbers

A private practice, any given month. The numbers are made up so they come out round; the method is the one we use.

Acquisition spend: 3,000 €

2,000 in Google Ads, 200 in tools (CRM and automation) and 800 in the hours of whoever runs it. Everything goes in.

New clients: 15

Not 60 appointment requests or 30 first visits: 15 people who paid for a treatment. The other numbers are conversion ratios, useful, but they are not clients.

CAC: 200 €

3,000 divided by 15. On its own it says nothing about good or bad: it depends on what each client leaves.

LTV: 1,500 € of margin

An average patient comes back twice and leaves 1,500 euros of gross margin over the whole relationship. It is the number almost nobody has calculated and the one that changes everything.

LTV:CAC ratio: 7.5:1

1,500 divided by 200. The system can scale: every euro in acquisition returns seven and a half in margin. With 300 euros of margin per client it would be 1.5:1, and each new patient would barely pay for what it cost to bring them in.

Payback: the first month

If the first treatment leaves 400 euros of margin, the CAC is recovered before the patient comes back. A payback longer than a year forces you to finance growth with cash or debt.

What a good LTV:CAC ratio is

Rules of thumb, not laws. Every business has its own, depending on margin and sales cycle.

Below 1:1, you lose money on every client

Even if sales grow. It is the case of many businesses that grow on ads: volume goes up and cash goes down.

Between 1:1 and 3:1, you survive but don't scale

The margin barely pays for the team and the tools. It usually means a conversion or retention problem, not a channel problem.

3:1 is the usual reference

With three euros of margin for every euro of acquisition, the system can take more investment. It is the figure most investors and operators use as the threshold.

Well above 5:1, you are probably underinvesting

A very high ratio in a small business usually says acquisition depends on word of mouth and there is room to build a channel of your own.

The mistakes that make CAC lie

Counting leads as clients

A form doesn't pay invoices. If you divide by requests, the CAC comes out cheap and the decision to invest is taken on a number that doesn't exist.

Forgetting hours and tools

The four weekly hours of whoever reviews the campaigns cost the same as a small agency. If they are left out, the channel looks more profitable than it is.

Mixing channels

A total CAC of 200 euros can be SEO at 40 and ads at 600. Only per channel can you see what to switch off and what to feed.

Measuring before the cycle closes

In a sale that takes three months, the CAC of a campaign's first month is always infinite. It is judged by the clients that spend ends up bringing.

Not separating new clients from returning ones

Acquisition brings new clients. The ones who come back are retention: another number, with another cost and another owner.

How to lower CAC without lowering the price

CAC comes down two ways: spend less per client, or convert more with the same spend. It almost always pays to start with the second. A landing page that converts twice as well halves the CAC without touching the budget; a form that qualifies stops you paying for appointments with people who were never going to buy.

Then, channels that compound: local SEO and content cost the same in month twelve as in month one and bring more every month. At Clínica Albareda, 82% of appointment requests come from Google without paying per click. And finally, LTV: a client who comes back or refers another halves the effective CAC. Raising the price does too, but that is no longer marketing, it is positioning.

What it looks like when it works

Laura Jové, an online health practice, multiplied booked appointments per month by 5 with a new website, SEO and Google Ads campaigns that return 15 euros of revenue for every euro invested. Clínica Albareda received 1,048 appointment requests in 2025 with 82% coming from Google, after three years of SEO: the organic channel's CAC falls every year that passes.

Both cases are published with their figures. We don't publish any client's absolute CAC: it is their number, not ours.

Selected projects

Embat

Fintech, Tech & SaaS

Clínica Albareda

Health

Laura Jové

Health

View all projects

A growth partner lives on CAC: it is paid on the new revenue it generates

A base plus a variable part tied to new clients, sized between 10% and 25% of the new revenue. If the CAC doesn't add up, neither does the invoice. What it is, what it costs and when it fits.

What a growth partner is

An opinion, signed

In ten years I haven't seen a business that sells something expensive with its CAC calculated properly the first time I asked. Almost all of them had a cost per lead from the ads agency and a hunch. The day they divide real spend by real clients, two things change: they stop arguing about channels and start arguing about conversion and retention, which is where the money was.

Marcel Garcia, founder of HAKI. If you want us to calculate yours with your data, start by telling us what you sell.

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CAC questions

Customer acquisition cost: everything you spend on acquisition in a period divided by the new clients, the ones who paid, that spend brought in. It is calculated per channel and compared with the margin a client leaves over the whole relationship (LTV).

Add up all acquisition spend in the period: media, tools, the hours of whoever runs it and the share of the website and content that exists to acquire. Divide it by the new clients that spend brought in, respecting the sales cycle (January's spend against March's clients if the sale takes three months). Do it per channel and use the total as a check. The guide has a worked example: 3,000 euros of spend and 15 new clients give a CAC of 200.

CPL is the cost per lead: a form, a call. CPA is the cost per specific action, often an appointment or a demo. CAC is the cost per client who has paid. Only the last one can be compared with the margin a client leaves; the other two are intermediate ratios, useful for optimising a channel, useless for deciding how much to invest.

3:1 is the usual reference: three euros of margin over the relationship for every euro invested in acquisition. Below 1:1 you lose money on every client even if sales grow; between 1:1 and 3:1 the business survives but doesn't scale; well above 5:1 usually means you are underinvesting and acquisition depends on word of mouth.

As soon as possible. In services, clinics and practices, the healthy case is that the first purchase pays the CAC; in a SaaS up to a year is accepted because the client pays every month. Beyond that, growth is financed with cash or debt, and every new client worsens cash flow before improving it.

First, conversion: landing pages, forms that qualify and automated follow-up lower CAC without touching the budget. Then, channels that compound, such as local SEO, which costs the same every month and brings more each time. And finally LTV: retention and referrals cut the effective CAC. Lowering the price is never on the list.