Cost per Acquisition (CPA) indicates the average cost required to generate a conversion defined as an acquisition: a sale, lead, signup or another valuable action.
How it works
It is calculated by dividing spend by the number of acquisitions. Unlike CAC, CPA can refer to any conversion and not necessarily a new customer, so the conversion event must be clearly defined.
Practical example
With $5,000 in spend and 250 attributed orders, order CPA is $20. If 80 orders come from new customers, media-only CAC for new customers would instead be $62.50.
Why it matters
It is useful for campaigns optimized toward a unit outcome and for comparing the efficiency of channels or segments with homogeneous conversions.
What to watch
A low CPA is not automatically positive: a conversion may have low economic value, insufficient margin or poor customer quality.