Customer Acquisition Cost Formula: How to Calculate CAC

The customer acquisition cost formula is simple: CAC = total sales and marketing spend ÷ new customers won in the same period. The hard part is deciding what counts as spend and what counts as a customer. If you get those two definitions right, you have a number you can use to set budgets and judge channels. If you get them wrong, you have a number that flatters you. At King Digital, we help Albuquerque businesses make this number honest, because every marketing decision after it depends on it.

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TL;DR

  • CAC is total acquisition spend divided by new paying customers over one period, as the American Marketing Association’s calculator frames it.
  • Count everything tied to winning customers: ads, agency fees, tools, sales and marketing pay, discounts and a share of overhead. Leave out retention costs.
  • Divide by booked jobs or paying customers, never by leads, calls or clicks.
  • Judge CAC against what a customer is worth, not on its own. A ratio around 3:1 lifetime value to CAC is a common target.
  • Calculate it by channel as well as overall, because a blended average hides your best and worst sources.

Table of Contents

The formula, step by step

Here is the formula in plain words:

CAC = (all money spent to acquire customers) ÷ (number of new customers acquired)

Both numbers must cover the same stretch of time. Spend from March divided by customers from April tells you nothing.

Two published examples show the arithmetic at different scales. One small-business guide divides $500,000 of quarterly marketing and sales cost by 1,000 new customers to get a $500 CAC. HubSpot’s guide uses ($300,000 + $100,000) ÷ 500 customers, which is $800 per customer. A simpler case: $1,000 of marketing and sales spend and 25 new customers gives a $40 CAC.

The formula never changes. What changes is your discipline in filling it in.

Step 1: Choose your period

Pick the window before you pull any numbers. Shopify’s guide suggests smaller businesses may track weekly or monthly, while businesses with longer sales cycles may prefer quarterly or annual periods.

A roofer or a remodeler, where a lead can take weeks to sign, should use a quarter so that spend and the customers it produced land in the same window. A restaurant or a salon can look at a month. If you run a campaign with a fixed start and end, such as a launch or an event, measure the whole run as one period. A week-by-week event marketing plan timeline helps you see when spend begins and when customers should start arriving.

Step 2: Add up what you spent

This is where most owners undercount. According to Shopify, the costs to include are:

  • Advertising (Google Ads, social ads, directories, sponsorships)
  • Content and creative (copy, photos, video, design)
  • SEO
  • Salaries and commissions for the people who market and sell
  • Agency and contractor fees
  • Software and analytics tools
  • Events and travel
  • Introductory offers and discounts
  • Professional services
  • An allocated share of overhead

What stays out is retention: loyalty rewards and emails to people who already bought from you. Shopify warns that mixing those in inflates CAC and hides how well acquisition is working.

Sales pay needs care. If you or a staff member spends half the week quoting new jobs and half doing the work, only the quoting half belongs in CAC. Acquire’s guide recommends including only the acquisition-related portion of sales compensation.

Step 3: Count only new customers

Use people who paid you for the first time in that period. Paddle’s guide says repeat purchases by existing customers belong in retention and lifetime value, not in the denominator.

For a service business, the denominator should be booked jobs or paying customers. Not quote requests, not phone calls, not form fills. A lead you paid for but never won is a cost, not a customer.

Step 4: Divide, then write down your definitions

Divide spend by customers. Then record what you counted as a customer and which costs you included. The AMA recommends documenting the customer definition and cost scope next to the number so you can compare periods fairly. Six months from now you will not remember whether the $400 intro discount was in the total.

Why the costs you include change the answer

A fully loaded CAC is almost always higher than the one you get from ad spend alone, and that gap is the point.

Glencoyne’s example spends $20,000 on ads, $14,000 on marketing salaries and $1,000 on software to win 100 customers. Counting ads alone gives $200. Counting everything gives $350, which is 75% higher.

HubSpot’s startup guide shows the same effect: a B2B startup that counts only ads and contractors gets $291.67 per customer, but $666.67 once founder time and CRM costs are included.

NetSuite’s worked quarter adds up like this:

Cost Amount
Sales salaries and commissions $30,000
Allocated overhead $10,000
Advertising $45,000
Software $8,000
Agency fees $7,000
Total $100,000

Divided by 1,250 customers, that is an $80 CAC. NetSuite’s view is that an artificially low CAC often comes from leaving out agency fees, commissions or similar costs, and that a fully loaded figure shows the real economics of growth.

Harvard Business School’s background note on CAC treats CAC as a managerial measure rather than a purely mechanical accounting one. You decide what an acquired customer is, which costs tie to acquisition and how to share common costs. Make those choices once, write them down and keep them stable.

Customer acquisition cost examples for a local service business

Here are three examples sized for the businesses we work with.

Example 1: A landscaping company

A landscaping guide walks through one month:

Cost Amount
Google Ads $800
Website hosting and tools $75
Yard signs (amortized) $40
Review-management software $30
Lead fees $200
Estimate labor $250
Estimate fuel $60
Total $1,455

With nine new customers, CAC is $1,455 ÷ 9, about $162. Notice that the time and fuel spent on estimates are in there. Many owners forget that quoting costs real money.

Example 2: An HVAC lead source

A lead-cost breakdown for home services shows why a price per lead is not your CAC. Buy 25 leads at $35 and you spend $875. If five turn into booked jobs, each job cost $175. If only four book, it rises to $218.75 per job. Same spend, different answer, because the denominator is customers, not leads.

Example 3: A cleaning business

A small-business walkthrough spends $1,800 on ads, $200 on booking and email software, $600 on a freelancer and $400 on introductory discounts. That is $3,000 for 30 new customers, so CAC is $100. The discounts count because they are the price of winning the first job.

What typical CAC looks like by trade

One 2026 contractor benchmark reports blended CAC ranges for small U.S. contractors:

Trade Blended CAC range
HVAC $250–$350
Plumbing $200–$300
Electrical $180–$260
Pest control $80–$150
Landscaping $120–$220
Handyman $120–$200
Roofing $350–$600
Cleaning $70–$150

Use ranges like these as a rough orientation, not as a verdict. Your own number only means something next to your own job values and margins.

What a good CAC looks like

There is no universal good number. A $300 CAC is excellent for a company whose average customer brings in $3,000 over time and painful for one whose customer brings in $250.

That is why CAC is read next to customer lifetime value (LTV), the total gross profit or revenue you expect from a customer over the relationship. A commonly cited target is an LTV to CAC ratio of about 3:1 or higher, though the right level depends on your business model. In the cleaning example above, a $450 lifetime value against a $100 CAC gives a 4.5:1 ratio.

A quick test for your own numbers:

  1. Calculate CAC for the period.
  2. Estimate what an average new customer is worth over the time they stay with you.
  3. Divide the second figure by the first.
  4. Check how many months of gross profit it takes to earn back the CAC.

If the ratio is thin or payback is slow, the fix is rarely just “spend less.” It may be a weak channel, a leaky website or slow follow-up.

Blended CAC versus channel CAC

One blended number is a start. A local-service guide shows $4,000 of monthly spend and 40 new customers giving a $100 blended CAC, and recommends calculating CAC per channel too, because averages can hide strong and weak channels.

Imagine Google Ads, Facebook ads and a directory listing are all in that $4,000. Ads might produce customers at $70 each while the directory produces them at $180. The blend of $100 tells you to do nothing. The split tells you where to move money.

Channel CAC depends on knowing which source each customer came from. That means tracking calls, forms and bookings back to their origin. Our guide to tracking marketing campaigns covers setup, and multi-touch attribution explains what to do when customers touch several channels before they call.

Blended Cac Versus Channel Cac

Mistakes that make CAC wrong

The AMA points out that small definition differences, such as what counts as a new customer, which costs are included, or whether you measure by click date or conversion date, can make CAC look better or worse than it is. The ones we see most:

  • Leaving out your own time. Estimating, answering leads and managing ads are acquisition work.
  • Dividing by leads. That gives you cost per lead, a different and friendlier number.
  • Mismatched timing. Ad spend in a month and customers who signed the next month belong to the same cohort when your sales cycle is long.
  • Mixing in retention. Review requests and thank-you offers to past customers are not acquisition costs.
  • Celebrating a low CAC. A cheap customer who buys once and leaves is worse than a pricier one who stays for years.
  • Ignoring missed calls. One home-services guide reports businesses spending $150–$350 per acquired customer on ads, then losing 62% of leads when the phone goes unanswered, which pushes real CAC to $394–$919. If your phone rings and nobody answers, your CAC is worse than your spreadsheet says.

Lowering CAC once you can measure it

CAC falls from two directions: spending less per lead, and turning more leads into customers. The second is usually faster for a local business.

  • Convert more of the traffic you already pay for. A clearer offer, faster page and simpler form lift the denominator without raising spend. Start with our guides to digital marketing conversion rate and customer conversion.
  • Shift spend to the cheapest channels. Channel CAC shows which ones those are. Organic local search tends to be among them, because a ranking keeps working after you’ve paid to build it.
  • Tighten paid campaigns. Wasted clicks on the wrong searches raise CAC directly. See what PPC management costs for US small businesses before you set a budget.
  • Connect CAC to revenue. Once you have it, our walkthrough on calculating marketing ROI shows how to turn it into a return figure.

How we help Albuquerque businesses with CAC

A CAC calculation is only as good as the tracking behind it. King Digital offers lead tracking, analytics tracking and conversion optimization alongside SEO, paid search and web design, so spend, leads and customers can be read in one place. We never lock clients into long-term contracts or withhold account access, so your numbers stay yours.

If you want a second set of eyes on your acquisition costs, we also offer consulting and advising to make sure your budget is spent efficiently. See our digital marketing services for the full list.

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Our perspective

I’m Bernadette King, and I started this agency after years as a business owner frustrated with big agencies that handed over reports nobody could connect to revenue.

Here is what we believe about CAC. It is not a vanity metric for investors. It is the answer to a plain question: what does it cost me to get a new customer, and is that worth it? Owners often ask us why their agency’s report looks great while the bank balance doesn’t. Usually the report counts clicks and leads while the real question is customers.

That is why we argue for tracking from the first day. When calls, forms and bookings are tied to the campaign that produced them, CAC stops being a guess. You can see which channel earns its place and which one is a leak. We also think you should have direct access to your own accounts and data, and the freedom to leave any time. A number you can’t verify is not much use.

Start with an honest, fully loaded CAC, even if it stings. It is the baseline every good decision after it depends on.

Bernadette

FAQ

What is the formula for customer acquisition cost?

CAC equals total sales and marketing spend divided by the number of new customers acquired in the same period. If you spent $6,000 in a quarter and won 40 new customers, your CAC is $150. Keep the spend and customer count on the same time window.

How do I calculate CAC for a small business with no sales team?

Use the same formula and include what you actually spend: ads, website and software costs, any agency or freelancer fees, discounts for new customers, and the value of your own time spent on estimates and follow-up. Divide by new paying customers, not inquiries.

Should I include my salary or my employees’ pay in CAC?

Include the portion spent on acquisition work, such as quoting, answering leads and managing marketing. Leave out time spent delivering work for existing customers. Excluding acquisition labor is one of the most common reasons CAC looks lower than reality.

What is the difference between CAC and cost per lead?

Cost per lead divides spend by inquiries, while CAC divides spend by customers who actually paid. If 25 leads cost $875 and five book, the cost per lead is $35 but the cost per acquired job is $175.

How often should I recalculate CAC?

Match it to your sales cycle. Monthly works for businesses that close quickly, and quarterly suits longer sales cycles. Track the same definition every time so the trend means something.

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