Home/Glossary/Customer acquisition cost (CAC)

Customer acquisition cost (CAC): definition

Analytics

By Alvyn Detavernier, founder · published October 28, 2026

Definition

Customer acquisition cost (CAC) is the average total cost of winning one new paying customer. It adds up ad spend, marketing and sales salaries, software and agency fees over a period, then divides that total by the number of new customers signed during the same period.

Also known as: CAC, Cost of customer acquisition, Blended CAC

The full formula

CAC = (marketing costs + sales costs) / new customers. Example for one quarter: $8,000 in ads, $5,000 of sales time, $1,500 in software and agency fees, so $14,500 for 29 new customers: a CAC of $500.

Teams often separate paid CAC, calculated only on customers who came from campaigns, from blended CAC, which includes customers from referrals and organic search. Blended CAC is lower, but paid CAC tells you whether advertising pays off.

Count costs in the period they were incurred and customers in the period they signed; with long sales cycles, a rolling three-month window smooths out the lag.

CAC vs CPA vs CPL

CPL is the cost of a lead, CPA the ad cost of a conversion, CAC the full cost of a paying customer. With a $50 CPL and one lead in five closing, ad cost per customer is already $250; add sales time and CAC can reach $400.

Payback period completes the picture: payback = CAC / (monthly revenue per customer × gross margin rate). A $500 CAC recovered in 4 months is easy to fund; recovered in 30 months, it takes serious cash reserves.

Lowering CAC

Be wary of CAC drops achieved by cutting investment across the board: CAC falls for a few months, then so does the number of new customers. The goal is a sustainable CAC at the volume you need, not the lowest CAC possible.

Raise your close rate: fast callbacks and a structured estimate follow-up sequence.
Qualify earlier so sales reps spend time on the right deals.
Grow channels with low marginal cost: referrals, reviews, organic search.
Cut campaigns whose paid CAC stays above one third of LTV for months.

Example

Example: with a $500 CAC and a customer who brings $120 in gross profit per month, payback takes just over 4 months. After that, every month of subscription is profit.

Frequently asked questions.

What is the difference between CAC and CPA?

CPA measures the ad cost of one conversion, often a lead, on a specific campaign. CAC measures the full cost of a paying customer across all channels, including salaries, software and agency fees. CAC is therefore always equal to or higher than a campaign's CPA.

What is a good CAC?

A good CAC is judged against customer value. The usual benchmark is an LTV to CAC ratio of at least 3 and a payback period under 12 months. A $2,000 CAC can be excellent for B2B software and ruinous for a consumer subscription box.

Related terms.

The concepts that go with it, to round out the definition.

Analytics

Customer lifetime value (LTV)

Customer lifetime value (LTV) is the revenue or gross profit a customer generates on average over their entire relationship with a business. It tells...

Paid advertising

CPA (cost per acquisition)

CPA (cost per acquisition) is the average amount of ad spend needed to generate one conversion, such as a sale, a quote request, a booked call or a...

Analytics

ROI (return on investment)

ROI (return on investment) measures how much an investment earns compared with what it cost. The formula is (net gain minus cost) divided by cost,...

Put it into practice.

Free tool

LTV Calculator

Glossary

Browse the full glossary

Digital marketing terms, from A to Z.

A second pair of eyes

Does this apply to your business? Let's look at your numbers.

In 30 minutes, we look at how this applies to your business, with your real data. Free, no commitment: you leave with a plan, even if we never work together.

Book a free call