Customer acquisition cost (CAC) is what it costs on average to win one paying customer: total sales and marketing spend divided by the number of new customers in that period.
Spend includes ads, sponsorships, paid launches, tools and, if you're honest, the value of your own time spent on marketing.
CAC is usually compared with customer lifetime value. If a customer is worth less than it costs to get them, growth loses money.
Why it matters for a launch
Knowing CAC per channel tells you which launches, directories or ads are worth repeating.