How much does one new customer cost you? This is a question service business owners ask less often than they should. Most know their advertising costs, but rarely connect them with the actual number of customers acquired. Yet this metric — CAC (Customer Acquisition Cost) — shows whether marketing spend brings results or just generates costs. In this text you'll find the formula, a table of what to include in acquisition costs, breakdown by channel, and the most common mistakes that inflate or deflate the result.
What is CAC and how to calculate it
CAC (Customer Acquisition Cost) is the total cost of acquiring one new paying customer over a specific period. The formula is simple, but the devil is in the details — especially in what to include in the numerator.
CAC formula:
CAC = total acquisition costs in period / number of new paying customers in the same periodThe result is expressed in PLN per customer. The key point is that we're talking about new paying customers, not just inquiries or leads. A lead is only a potential customer — only when they sign a contract, place an order, or pay for the first service do they count as an acquired customer. The difference is fundamental: a company might have a hundred leads per month, but if only five become customers, CAC calculated from a hundred leads will be five times lower than CAC calculated from five customers.
The period must be the same in the numerator and denominator. If you calculate costs for the entire year but only count customers acquired in December, the result will be unrealistic. Typically, a month or quarter is used, depending on the sales cycle in your industry.
Why not count from leads
A lead is only first contact — a person who sent an inquiry, called, or filled out a form. Only when that lead becomes a paying customer can we talk about successful acquisition. Counting CAC from the number of leads instead of the number of customers inflates channel effectiveness and leads to wrong budget decisions.
What to include in acquisition costs — table
Not everything you spend on marketing goes into CAC. Here's what should be included and what should be omitted:
| Category | Include in CAC? | Notes |
|---|---|---|
| Paid advertising (Google Ads, Facebook, portals) | Yes | Total campaign cost for the period |
| Portal and platform commissions (Booksy, Zumi, OLX) | Yes | Fees for leads or transaction commissions |
| Team time handling leads | Yes | Hours × hourly rate; not just sales staff but also reception |
| Tools (CRM, phone system, SMS, e-mail) | Yes | Portion of costs proportional to new customer handling |
| Subcontractors (freelancers, agencies) | Yes | Cost of services related to customer acquisition |
| First visit with discount | Yes | Difference between regular price and new customer price |
| Maintaining existing customers | No | That's service cost, not acquisition |
| General team training | No | Only training related to acquisition |
| Office equipment | No | One-time expense, not recurring cost |
The most common mistake is including work time without hourly valuation or omitting tool costs. In a service business, time spent on answering phones, replying to messages, and scheduling appointments is a real cost that must be valued.
How to value team time
Team time spent on lead handling includes all activities from first contact until the lead becomes a customer. Include time spent on phone calls, replying to e-mails and messenger messages, scheduling appointments, and follow-up with people who didn't respond right away. The hourly rate is the average rate of all people involved in this process, not just salespeople.
Example on illustrative numbers — plug in your own
Example on illustrative numbers — plug in your own. Assume a service business that spends in one month on customer acquisition: 4000 PLN on Google Ads, 600 PLN Booksy commission, 1000 PLN for team time on leads (20 hours × 50 PLN/hour), and 400 PLN on tools — together 4000 + 600 + 1000 + 400 = 6000 PLN. In the same month the business acquired 15 new paying customers, so CAC = 6000 PLN / 15 customers = 400 PLN per customer.
CAC by channel — why one average is not enough
Calculating a single average CAC for the whole company misses the point. A customer from Google Ads costs differently than from a referral or a industry portal. To truly see channel effectiveness, you must separate costs and customers by source.
How to do it in practice:
- Every first customer contact — the question "how did you find us?" — is an opportunity to tag the source in your CRM.
- Costs from ad dashboards (Google Ads, Facebook) are assigned to specific campaigns and sources.
- Portal commissions and tools are allocated proportionally to lead volume from each channel.
- Team time is divided according to where leads handled in the period came from.
Example on illustrative numbers — plug in your own:
| Channel | Monthly costs | New customers | CAC |
|---|---|---|---|
| Google Ads | 3200 PLN | 8 | 400 PLN |
| Referrals | 200 PLN | 5 | 40 PLN |
| Booksy | 900 PLN | 6 | 150 PLN |
| Google Business profile | 100 PLN | 4 | 25 PLN |
Still on illustrative numbers: referrals (40 PLN) and Google Business profile (25 PLN) are the cheapest channels, but have limited volume — 9 customers combined. Google Ads generates the highest number of customers (8), but at a CAC sixteen times higher than Google Business profile. Budget decision depends on how much the company can spend on acquisition and what CAC is acceptable for them.
A customer who came through two channels
Sometimes someone first sees an ad, doesn't act, then comes through a referral. In this case, assign the customer to the first contact channel — that's what motivated initial interest.
Websites without clickable phone — cost of lost leads
These numbers come from our analysis of Warsaw business websites in that industry (July 2026); the share is calculated from the sites we managed to open.
If your own site is one of them, every visitor on a phone has to manually copy the number instead of tapping it — an extra step where some interested people simply give up. In a service business where phone is often the first contact channel, that's a concrete obstacle to remove, even if it can't be converted into a currency amount upfront.
Check first whether your own website has a clickable phone number — that's one of the basic things to fix before you start counting the cost of lost calls.
Learn more about how much missed calls cost in a company — a formula to calculate with your own numbers.
CAC vs customer value — when the investment returns
CAC alone doesn't tell you if you're spending too much or too little. Only comparison with customer value (Lifetime Value, LTV) shows whether a channel is profitable. In service businesses, customer value is the sum of margin from all their orders or services throughout the cooperation period.
Simple profitability test:
CAC payback period (in months) = CAC / (average monthly margin per customer)Example on illustrative numbers — plug in your own data: with a CAC of 400 PLN and an average monthly margin of 250 PLN per customer, payback period = 400 PLN / 250 PLN = 1.6 months. Depending on the industry, such a result may be acceptable or not.
In service businesses with long decision cycles (e.g., B2B services, renovations, legal services) the first order margin often doesn't cover CAC. Only repeat orders or long-term cooperation make the channel profitable. That's why calculating CAC only on the first order is misleading in such businesses — you should consider the projected value of the entire cooperation.
Own databases and marketing consents
Sending SMS or e-mail offers to your own customer database is cheaper than paid advertising, but has its rules. Article 398 paragraph 1 of the Electronic Communications Law (Dz.U. 2024 poz. 1221) states that using automatic calling systems and telecommunication terminal equipment for direct marketing purposes toward a subscriber or end user is prohibited unless they have previously given consent (full text of the act, art. 398).
This means even to your own customer database you cannot send commercial SMS, e-mails, or make automated calls without prior consent. In practice, this means the "cheap" channel of customer acquisition through marketing to your own database requires prior consent collection — which is itself a cost (time, tools, process). You cannot assume your own database is always cheaper than paid advertising — you must include the cost of maintaining consents and keeping them updated.
Whether a specific message is marketing, or if it complies with existing consent — a lawyer or IOD (Data Protection Officer) will assess.
AI in marketing — context, not a benchmark
Artificial intelligence technologies are becoming part of marketing, but it's worth separating reality from hype.
The survey covers enterprises with at least 10 employees.
These numbers are not a CAC benchmark. They don't say a company should spend a specific amount on AI. They only show that AI adoption in marketing is still low, and companies that start may gain an advantage. Introducing AI doesn't automatically lower CAC — only specific applications (e.g., automatic reply to inquiries, ad personalization, lead prediction) can affect acquisition cost.
Learn more about process automation costs in 2026 and what changes them.
Most common CAC calculation mistakes
Different periods in numerator and denominator. You calculate annual costs but divide by customers from one month — the result will be unrealistically high or low.
Inquiries instead of customers. Many companies divide costs by lead numbers instead of actually acquired customers. CAC is then several times lower than in reality.
Omitting team time. Advertising cost alone is often less than half of the real CAC. Time spent on lead handling, scheduling appointments, and follow-up is a real expense.
One average result without channel breakdown. Average CAC can hide a cheap channel and an expensive channel. Without breakdown you don't know where to optimize.
Including brand advertising in a specific channel's CAC. Building brand awareness is a long-term investment, not an acquisition cost for a specific channel.
No source tracking. Without asking "how did you find us?" and without tagging sources in CRM, it's impossible to calculate CAC by channel.
Learn more about why customers don't leave inquiries — what the analysis of Warsaw company websites shows.
Do it yourself — quarterly table
Create a spreadsheet with the following columns:
- Channel (Google Ads, Booksy, referrals, Google Business profile, direct)
- Costs (advertising + commissions + work time + tools)
- New customers (actually acquired in the period)
- CAC (cost / customers)
Fill in data for the last quarter. Draw three conclusions from the table:
- Which channel has the lowest CAC? Can you increase its budget without exceeding acceptable cost?
- Which channel has the highest CAC? Does its customer value justify the cost, or should it be optimized or limited?
- Is total CAC lower than average first order value? If not — you either need to lower acquisition costs or increase first order value.
Regular CAC calculation (monthly or quarterly) lets you spot trends: whether costs are rising or falling, and why.
Learn more about restaurant marketing ROI measured on margin — how to calculate RORAS for a service business.
How it looks in a system — why you need these numbers
Every customer's source is recorded at first contact — the question "how did you find us?" and CRM tagging is the foundation. Next to the source you put the cost: inquiries, calls and bookings with their cost broken down by channel, and the summary comes to you on its own on a set day, instead of waiting for someone to open a dashboard.
The report includes cost and customer breakdown by source, comparison with the previous period, and identification of channels needing attention. You as the owner decide how much you can spend to acquire one customer and which channel is optimal for your company. This is not a promise to lower CAC — it's a tool that shows you real numbers so you can make informed budget decisions.
See what reporting looks like that shows you numbers that really matter for an owner — without unnecessary tables. AI Reports deliver a summary of leads, campaigns, and sales in simple language, sent on their own on a set day. Instead of a dashboard nobody checks, you get concrete numbers you can rely on.
If you want to go further, combine reporting with the CRM and automations service so calls, forms and your Google Business card feed into one place, and customer source is tagged from first contact.
Also check the Analytics and BI service: how much one inquiry really costs and where customers come from. You start with a free preliminary audit, then have ongoing measurement: inquiries, calls, bookings and their cost broken down by channel.
Also consider Google Ads, Finance and Integrations to connect data from different sources.
Learn more about why customers don't leave inquiries and what impacts lead losses.
Frequently asked questions
Should CAC be lower than first order value?
Not always. In service businesses with long cooperation cycles, the first order may not cover CAC, but repeat orders and long-term relationships make the channel profitable. The key is calculating CAC in relation to projected value of entire cooperation, not just first contact.
How often should you calculate CAC?
Monthly or quarterly — depending on customer acquisition volume. In high-volume businesses, monthly cycle is enough. In businesses with long sales cycles (B2B services, real estate) quarterly works better to have enough data.
What to do when CAC rises month over month?
Check if it's rising across all channels or just one. If just one — investigate whether effectiveness changed (fewer customers at same costs) or costs increased (more expensive clicks, higher commissions). Then decide: optimize the channel (better creatives, narrower targeting) or shift budget to cheaper channels.
Do referrals really have near-zero CAC?
Near-zero direct cost, but not total zero. A satisfied customer who refers probably received good service first — meaning quality cost is included in price. Additionally, companies sometimes give small gifts or discounts for referrals, which should be included.
How to tag sources in practice?
Simplest — ask at first contact and enter source in CRM. You can also use dedicated phone numbers for different channels, UTM parameters in ad links, and unique promotional codes. Important: the tagging system should be simple — the more steps, the less likely the team will do it consistently.