What is CPA? Cost per acquisition explained

CPA (cost per acquisition) is the average ad spend needed to generate one conversion, usually a purchase.

How is CPA calculated?

CPA = ad spend ÷ number of conversions

Example

Spending $2,800 to get 100 purchases gives a CPA of $28.

Why does CPA matter for e-commerce?

CPA is easier to compare with your product margin than ROAS: if a first order earns $35 in gross profit, any CPA below that is profitable on the first purchase.

How does Posta use CPA?

Posta's agents use CPA when reviewing your accounts and recommending changes. See the AI media buying page for how it fits into your workflow.