Patient acquisition cost (CAC) in HOF

Many orofacial harmonization (HOF) clinics invest in ads, content and referrals without knowing how much each new patient costs. They look at the number of messages received and conclude that "it's working," but do not know whether the patient who signs up pays for what was spent to bring them in. Patient acquisition cost (CAC) answers that question with a simple division.

This guide explains what goes into the calculation, how to work it out step by step, how to compare it with the patient's value over time (LTV), how to compare channels and what to do when CAC is high. The numbers in the examples are fictional. Advertising rules in healthcare vary by council and you should check them yourself (see paid ads for HOF within the rules).

What is CAC and why does it matter?

CAC is the total spent to win new patients, divided by the number of new patients who signed up in the same period. The decisive word is "signed up": messages, likes and bookings do not pay the bills. CAC connects the investment to the financial result and lets you answer:

• Is this channel worth what it costs?
• Can I increase the investment without hurting margin?
• Is it better to invest in winning new patients or in getting current ones to come back?

For a small clinic, CAC also shows something intuition hides: the patient who arrives through a referral usually costs less, and the patient who arrives through a cold-audience ad usually costs more. That difference guides where to put time and money.

What goes into the CAC calculation?

The honest calculation includes everything spent to attract and convert the patient, not just the amount paid to the ad platform:

It takes work, but it pays off: a simplified version (ads only) can make CAC look low and hide an expensive channel.

How do you calculate it, step by step?

1. Choose the period (a month, a quarter) and the channel (ads, referrals, organic).
2. Add up the costs of the channel in the period.
3. Count the new patients who signed up from that channel (those who paid for a procedure, not just booked an assessment).
4. Divide: CAC = costs for the period ÷ new patients who signed up.

To know where patients came from, ask at first contact ("how did you find us?") and record it on the patient form. Without that, CAC is a guess.

Funnel: where the cost gets lost

Cost per lead is only the beginning. The patient goes through stages, and each stage loses people:

Hypothetical example: in one month, the clinic invests R$ 4,000.00 in ads and another R$ 800.00 in content production for that channel, a total of R$ 4,800.00. 120 contacts come in. Of these, 36 book an assessment, 28 attend and 10 sign up.

Notice that cost per lead (R$ 40.00) looks small, but CAC is twelve times larger. Whoever decides by looking only at cost per lead underestimates the real investment. Each point where the funnel improves (fewer no-shows, higher acceptance) lowers CAC without spending more on ads.

Good or bad CAC? Compare it with LTV

A CAC is only high or low relative to the value the patient leaves. That value is LTV (patient lifetime value), which should be measured in margin, not revenue. The patient LTV calculator helps estimate it.

Hypothetical example: in the example above, CAC is R$ 480.00. Suppose the clinic's average patient generates a margin of R$ 1,800.00 over 12 months, counting returns and maintenance. The ratio is 3.75 times (R$ 1,800.00 ÷ R$ 480.00). If, in another channel, CAC were R$ 1,700.00, the R$ 1,800.00 margin would barely cover the cost and the patient would only be worth it if they came back more than once.

Two important notes:

• LTV depends on the patient coming back. That is why investing in return visits and loyalty and in recall affects the acquisition math.
• Margin is not revenue. See profit margin in HOF and average ticket in HOF.

Which channels usually have a different CAC?

There is no fixed ranking, but there are ways of thinking that help:

The best channel is usually the one that combines a reasonable CAC with a patient who comes back. A cheap channel that brings people who only ask the price can end up costing more than an expensive channel that brings people who sign up for the full plan.

How do you lower CAC without cutting quality?

The fastest way to lower CAC is rarely to spend less on ads. It is to improve what happens after the contact:

• Reply fast and with a script. See WhatsApp scripts for an HOF clinic.
• Reduce no-shows with confirmation and a clear policy, since every no-show is an acquisition cost lost.
• Improve how you present the plan: the before and after in the consultation, a quote the patient understands and the post-consultation follow-up raise acceptance.
• Win back those who went silent after the quote. See patients who vanish after the quote.
• Encourage referrals from those who already trust the clinic, taking care with the rules.
• Qualify the ad audience, so fewer curious people and more people with real interest arrive. This raises cost per lead, but usually lowers CAC.
• Ask for reviews and look after the local profile. See replying to Google reviews.

How much should you invest in ads?

A rational way to decide is to start from three questions:

1. What is the margin of a new patient in the first year (LTV in margin)?
2. How much of that margin does the clinic accept spending to win them, while keeping a profit? Set a CAC ceiling.
3. Can the schedule handle more patients? Investing more without capacity only creates queues and frustration.

Start with a small amount, measure CAC for 2 or 3 months and only then increase. Scaling ads with a broken funnel multiplies waste. And remember that, in healthcare, ad content has rules: no promise of results, no sensationalism and in line with the council (see what you may advertise).

Common mistakes

• Calculating only cost per lead and calling it CAC.
• Counting a booking as a sign-up.
• Ignoring the team's time and content production.
• Not asking where the patient came from.
• Comparing CAC with revenue instead of margin.
• Switching channels every week, with no time to measure.
• Investing more with a full schedule or a broken funnel.
• Forgetting that the patient who comes back pays the CAC again.

Where Harmy fits in

Harmy does not manage ads. It works at the point in the funnel where the most money is lost: the consultation. The projection is generated from the front-facing photo, with ml per area, and the Before/After slider helps the patient understand the plan. The quote PDF comes out with the clinic's name and logo, with price per ml per area and validity. If this raises acceptance, CAC falls without spending more to bring people in. Each projection costs R$ 3.99, with no monthly fee; the calculator for projections that pay for the app shows the math. Always remember that the projection is an illustrative simulation, not a promise of results.

CAC checklist

• Did I define the period and the channel?
• Did I add up ads, content, tools and team time?
• Do I record where each new patient comes from?
• Do I count only those who signed up, not those who merely asked?
• Did I compare CAC with the patient's margin (LTV)?
• Do I know at which funnel stage I lose the most people?
• Did I set a CAC ceiling before raising the investment?
• Did I check my council's advertising rules?

CAC is not a number to impress, it is a tool for deciding. With it, the clinic chooses channels by what they actually bring in, invests with a ceiling and starts treating the funnel, not just the ad, as the place where money is won or lost. See also the HOF clinic indicators.