How to Calculate Cost to Acquire a New Customer

My father ran a hardwood-floor business in Southern California with a crew of 25. A partner developed a drug habit and embezzled. Payroll bounced, payroll taxes went unpaid, the IRS came after him, and the house went into foreclosure.

And here's why that matters to your business. A company runs on numbers it trusts, and a number is only as good as the records behind it. If you run a company at $5M or more in revenue, you probably have a CAC figure somebody gave you in a slide. Would it survive a stranger rebuilding it from your bank statements and payroll?

That stranger exists if you plan to sell. A buyer's diligence team will recalculate the figure from the raw records and add back every cost you left out. I covered what that does to your value in Customer Acquisition Cost: What the Number Hides. This article is the procedure underneath it, the way to build the number so it holds up.

What is the formula for customer acquisition cost?

The formula is total acquisition spend divided by new customers acquired in the same period. The American Marketing Association's calculator describes it as "the core formula: total acquisition spend divided by new customers in the same time period."

The arithmetic takes ten seconds. Zendesk gives a worked example: a company spent $150K on marketing and $100K on sales in a quarter and won 300 new paying customers. Its CAC for that quarter is $833, worked out as (150,000 + 100,000) / 300.

Sales and marketing share one numerator there, and that's the minimum. The division is easy. The fight is always over the top number, so that's where the rest of this article spends its time.

Which costs belong in the numerator?

Every cost you'd stop paying if you stopped trying to win new customers belongs in it. That includes ad spend, but it also includes the people, the software and the agencies around the ad spend.

Revenue Grid's calculator tells you to add up "salaries, commissions, tools (CRM, sales enablement platforms, etc.), training, travel, and overhead" on the sales side.

I start with payroll and accounts payable, not the marketing dashboard, because the dashboard only knows about the spend it can see. The table runs that check line by line.

Cost line	Usually counted?	Where to find it	Include it?
Paid media (Google, Meta, LinkedIn)	Yes	Ad platform invoices	Yes
Agency and contractor fees for marketing	Often missed	Accounts payable	Yes
Marketing team salaries and benefits	Often missed	Payroll	Yes, the share spent on new customers
Sales salaries and base pay	Sometimes	Payroll	Yes, the share spent on new customers
Commissions and bonuses	Sometimes	Payroll	Yes
CRM, sales and marketing software	Often missed	Software subscriptions	Yes
Events, travel, training	Often missed	Expense reports	Yes
Your own time selling	Almost never	Nowhere, so you have to estimate it	Name it, even if you can't price it

The last row is the one owners skip. In a lot of owner-led companies, the founder is the best salesperson. If your calls produce a big share of new customers and your salary isn't in the number, the CAC is lower than the truth. A buyer will spot that fast, because the first thing they ask is who closes the deals and what happens when you leave.

How do you split a salary between new and existing customers?

You allocate the salary by how the person spends their time. You don't count 100% of someone who also looks after existing accounts.

Maxio gives a clean example: "Suppose a salesperson earns a $100,000 base salary, but their time is split 70/30 between chasing new customers and nurturing existing ones." In that case, Maxio says, "it makes sense to allocate only $70K of the base salary rather than the full $100K to your cost of acquisition."

The rule runs both ways. Maxio also says "CAC should only account for the costs associated with acquiring new customers," so account managers who only renew and upsell stay out. Revenue Grid says the same about the denominator: count only net new customers and exclude upsells, cross-sells and renewals.

Write the split down, with the percentage and the reason in a note next to the number. If the 70/30 lives in one person's head, you've built a number that depends on a hero.

Which time period should you use?

Use a period long enough to cover your sales cycle, and line up spend with the customers it actually produced. A quarter is a common choice. If your sales cycle runs ninety days, though, this month's spend didn't create this month's customers.

CXL walks through the lag with a free-trial product. If it takes 30 days on average for trial users to become paid customers, "the 1100 new customers in March are the result of February's acquisition cost." You'd divide the earlier month's spend by the later month's customers.

Most $5M+ companies have a longer lag than a free trial. A marketing-services firm or a healthcare practice group often signs a contract a quarter after the first conversation. If that's you, compare spend from the quarter before with customers closed in the quarter after. A trailing twelve months smooths the lag too, and it's the view a buyer takes of your history.

Pick one. Keep it. A number that changes definition every quarter can't be compared with itself.

What are the steps to run it?

1. Choose the period and write it down, including how you'll handle the lag between spend and close.
2. Pull every cost line from the table above out of payroll, accounts payable and expense reports, not from the marketing dashboard.
3. For anyone who splits time between new and existing customers, allocate their pay by the share spent on new customers, and record the percentage.
4. Count only net new customers for the same period, and exclude upsells, cross-sells and renewals.
5. Divide the total by the customer count.
6. Store the definition next to the number: what's in, what's out, who decided.

The American Marketing Association's calculator makes the last step explicit and tells you to "document your customer definition and cost scope alongside the number." Without that note, nobody can tell your CAC from a guess.

What does a good result look like?

A good CAC is one that's low compared with what a customer is worth, and the most common yardstick is the LTV to CAC ratio. Wikipedia's entry on CAC lists 3:1 as "a very good level because the customer relationships are solid and customers are acquired for the right price." Below 1:1, the company is paying more for customers than they're worth.

CXL puts the threshold the same way: the ratio should be at least 3 for a sustainable business, and under 3 is a red flag for overspending on acquisition. Treat 3:1 as a rule of thumb, not a law. A company with high margins and long retention can run it lower. A company with thin margins can't.

If you just dropped salaries into the numerator, your ratio got worse. That's correct. A ratio you can defend is worth more to a buyer than a better-looking one you can't.

How does the full-cost version change what a buyer sees?

It changes the number, and it changes how much they trust every other number you give them. A buyer who finds one omitted cost starts looking for the next one.

Say you report a CAC built from ad spend alone. The diligence team adds the sales team, the agency retainers and the software. The CAC rises, the LTV to CAC ratio falls, and the buyer is now negotiating from a number you didn't give them.

The second thing they check is repeatability. If most new customers came through your personal network or one salesperson's relationships, the CAC may be real and still be worth little. A company's value is capped at the level its CEO is comfortable running, and a CAC that only works while you're in the room is part of that cap. Buyers pay for systems, not heroes.

So add one more column to your work. For each channel, ask whether it would keep producing customers if you disappeared for ninety days. If you want to see where else the value is leaking, the assessment covers the whole business, and the blog goes deeper on key-person risk.

What are the common mistakes?

The most common mistake is counting only ad spend. It's the easiest number to pull, and it leaves out every person and tool that turns a click into a signed customer. Salaries, software and agency fees are acquisition cost, and leaving them out flatters the result.

The next one hides in the denominator. If renewals and upsells sit in the count, CAC drops for a reason that has nothing to do with winning new business, so keep it to net new customers.

Timing catches people too. Matching this month's spend to this month's customers works for a product with a same-day sale, and it misleads you when deals take a quarter.

Then there's your own time, the cost you can't price but can name. A line in the notes that says "owner closes roughly this share of deals, salary not included" does more for your credibility than a clean number that hides it.

Last, don't change the definition and compare across periods anyway. If the scope shifted, say so, or restate the old periods.

FAQ

What is a good CLV to CAC ratio?

The most common benchmark is at least 3:1, meaning a customer is worth three times what it cost to win them. Zendesk calls 3:1 the agreed-upon sweet spot. Your margins and retention decide whether you can run lower.

How do you compute the acquisition cost?

Add all sales and marketing costs spent on winning new customers in a period, including salaries, commissions, tools and agency fees. Divide by the net new customers won in the same period. Allocate shared salaries by the time spent on new customers.

What does customer acquisition mean?

Customer acquisition is the work of winning a first purchase from someone new. Wikipedia defines CAC as the cost of persuading a customer to purchase a product or service. Renewals and upsells to existing customers aren't acquisition.

What is the average cost to acquire a new customer?

There's no honest single average, because it swings by industry, deal size and sales cycle. One reference point: Revenue Grid's calculator treats $1,000 to $5,000 as healthy for most B2B businesses. Compare yourself against your own customer value first.

What should you do today?

Open last quarter's payroll, accounts payable and expense reports, and list every line that exists to win new customers. Mark any shared salary with a percentage and a one-line reason. Then divide the total by net new customers and save the definition beside the result.

If a buyer rebuilt this number from your raw data next week, would it match yours?