What is CPA?
CPA (cost per acquisition) is what one order or customer costs you in ads.
CPA connects ad spend with results. For e-shops it is usually cost per order.
Compare CPA with your break-even CPA, which is order value times margin. Below it you earn, above it you lose.
Formula
CPA = ad spend / conversions
Example
You spend 600 EUR and get 30 orders. CPA is 20 EUR.