Subscriber Acquisition Cost, or SAC, is the amount of money a company spends for each new subscriber they gain.
As its title would suggest, subscriber acquisition cost is a metric that is primarily used by companies that offer some sort of subscription based service, like telecommunications companies or cable television providers. Measuring these costs on a per-customer basis is helpful when determining how expensive specific offerings are for the company. This can also be useful when compared to other per-customer based metrics like Average Revenue Per User (ARPU). SAC is most commonly calculated using costs that are specific to attracting new customers, like marketing spending.