What is CAC?
Nicklas Segatz Mortensen · Growth Hacker · Fractional CMO · Meta Ads Nerd · 8 July 2026 · 5 min.
Definition
CAC (Customer Acquisition Cost) is your total sales and marketing costs divided by the number of new customers in the same period. It's the price of winning one customer.
Also called: Customer Acquisition Cost, Cost of acquisition
Sådan virker det
CAC = marketingforbrug delt med antal nye kunder. 100.000 kr. og 200 kunder giver en CAC på 500 kr. Men tallet siger først noget, når det holdes op mod kundens værdi over tid (CLTV).
01How CAC is calculated
CAC = total marketing and sales costs / number of new customers. Spend €13k and win 200 new customers, and CAC is €65. Simple — but the trap is that many count every order rather than only the new customers.
It's an important distinction: a large share of your orders come from existing customers buying again. Mix them in, and acquisition looks artificially cheap. That's why we work with nCAC — CAC on new customers only.
02CAC without CLTV is meaningless
A CAC of €65 is neither good nor bad on its own. It has to be held against what the customer is worth over time (CLTV). If the customer is worth €330, the ratio is 5:1 and healthy. If the customer is worth €80, you're burning money.
That's why the CLTV:CAC ratio is one of the most important numbers in the whole business — and why we never optimize CAC in isolation.
03Blended CAC, marginal CAC and a worked example
There are three CACs worth knowing. Blended CAC is all marketing spend divided by all new customers — the honest total picture. Paid CAC looks only at the paid channels. And marginal CAC is the most important one when scaling: what does the next customer cost? You win the cheapest customers first, so marginal CAC rises the more you scale — and it's the marginal number, not the average, that decides when more budget stops being profitable.
An example: you spend €13k and win 200 new customers — blended CAC €65. If the average customer is worth €330 in contribution margin over their lifetime, CLTV:CAC is 5:1, and there's plenty of room to scale. But double the budget to €26k and only get 320 new customers, and the last 120 customers cost roughly €108 each. That's the marginal economics telling you whether the last budget still turned a profit.
So a falling average CAC isn't always good news, and a rising one isn't always bad. What matters is whether the marginal customer is still profitable inside their payback period.
Frequently asked questions
What is a healthy CLTV:CAC ratio?+
The rule of thumb is 3:1 or better — the customer should be worth at least three times what it costs to win them. Below 1:1 you lose money on every customer; well above 3:1 can mean you're underinvesting in growth.
What's the difference between CAC and nCAC?+
CAC is often calculated across all orders. nCAC counts only new customers and is more honest, because it doesn't let repeat purchases mask the real price of winning a new customer.
Related terms
Glossary
What is nCAC?
nCAC (new Customer Acquisition Cost) is marketing spend divided by the number of first-time buyers. Unlike ordinary CAC, it counts only new customers — not repeat purchases from existing ones.
Read the entry →Glossary
What is CLTV?
CLTV (Customer Lifetime Value) is the total gross profit an average customer contributes across their entire lifetime as a customer — from first purchase to last.
Read the entry →Glossary
What is payback period?
Payback period (CAC payback) is the time it takes before the profit a new customer generates has covered what it cost to acquire them. The shorter the payback, the faster capital can be reinvested in growth.
Read the entry →
Nicklas Segatz Mortensen
Growth Hacker · Fractional CMO · Meta Ads Nerd at Oaksmond
Growth hacker and fractional CMO with 10+ years' experience and hundreds of millions in managed ad spend behind him. Background from larger Danish and international scale-ups, and from the agency world.
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